1 00:00:01,690 --> 00:00:06,759 How much, in modern dollars, did the Colosseum cost to build? 2 00:00:06,759 --> 00:00:10,730 And how much would it cost to build an exact replica today? 3 00:00:10,730 --> 00:00:14,500 We’ll start with the first question. 4 00:00:14,500 --> 00:00:21,259 The Romans reckoned costs in sestertii, big brass coins worth a quarter of a denarius. 5 00:00:21,260 --> 00:00:26,840 At the time the Colosseum was built, one sestertius could buy two loaves of bread, four cups of 6 00:00:26,839 --> 00:00:30,719 cheap wine, or a single cup of good wine. 7 00:00:30,719 --> 00:00:36,488 A tunic cost about 15 sestertii, and the rent for a decent apartment was probably between 8 00:00:36,488 --> 00:00:40,599 300-500 sestertii a year. 9 00:00:40,600 --> 00:00:46,189 The average annual wage for an unskilled laborer was around 1,000 sestertii. 10 00:00:46,189 --> 00:00:51,119 A marble mausoleum along the Via Appia could easily cost 10-20,000 sestertii. 11 00:00:51,119 --> 00:00:58,408 A wealthy senator could spend 300,000 adding a private bath to his house. 12 00:00:58,408 --> 00:01:03,728 Simply finishing Nero’s Golden House cost 50,000,000 sestertii. 13 00:01:03,728 --> 00:01:06,500 How did the Colosseum compare? 14 00:01:06,500 --> 00:01:11,549 Since no literary source or inscription provides any clues, we have to estimate on the basis 15 00:01:11,549 --> 00:01:14,759 of labor and material costs. 16 00:01:14,760 --> 00:01:19,570 The first task of the Colosseum’s builders was to excavate the foundation trench, as 17 00:01:19,569 --> 00:01:23,429 large as the building’s footprint and more than 8 meters deep. 18 00:01:23,430 --> 00:01:30,340 Removing something like 170,000 cubic meters of earth and stone was an enormous task, involving 19 00:01:30,340 --> 00:01:32,700 thousands of workers. 20 00:01:32,700 --> 00:01:37,439 Contrary to what you might assume, few of them were slaves: although the private contractors 21 00:01:37,439 --> 00:01:42,609 who built the Colosseum had small permanent staffs of skilled slaves and freedmen, most 22 00:01:42,609 --> 00:01:47,019 of the work was done by unskilled day laborers. 23 00:01:47,019 --> 00:01:52,689 Following an approach pioneered by Janet DeLaine, a professor of Roman archaeology at Oxford, 24 00:01:52,689 --> 00:01:57,599 I used a nineteenth-century construction manual to estimate the labor required to clear the 25 00:01:57,599 --> 00:02:01,109 Colosseum’s foundation trench with hand tools. 26 00:02:01,109 --> 00:02:07,079 If I did the math right, something like 70,000 man-days of labor would have been required 27 00:02:07,079 --> 00:02:12,669 to excavate and haul away 170,000 cubic meters of rocky soil – but this does not account 28 00:02:12,669 --> 00:02:16,691 for the fact that the workmen had to cut into bedrock on the north side of the foundation 29 00:02:16,692 --> 00:02:21,189 trench, and had to contend with a high water table throughout. 30 00:02:21,189 --> 00:02:27,139 So let’s say, conservatively, that 125,000 man-days of labor were required. 31 00:02:27,139 --> 00:02:32,419 I’ll assume that the workmen earned an average of 4 sestertii a day, which seems to have 32 00:02:32,419 --> 00:02:36,299 been the going rate for a laborer in first-century Rome. 33 00:02:36,300 --> 00:02:40,230 By that reckoning, the cost of clearing the Colosseum’s foundation trench was in the 34 00:02:40,229 --> 00:02:43,609 neighborhood of 500,000 sestertii. 35 00:02:43,610 --> 00:02:46,990 Next, the foundations were laid. 36 00:02:46,990 --> 00:02:51,650 Like the building above it, the Colosseum’s foundation was a huge ellipse about 60 meters 37 00:02:51,650 --> 00:02:52,890 wide. 38 00:02:52,889 --> 00:02:59,250 It consisted of two parts: a lower foundation of solid concrete 7 meters thick, and a 6 39 00:02:59,250 --> 00:03:06,050 meter thick upper foundation, also concrete, honeycombed with service passages. 40 00:03:06,050 --> 00:03:11,380 Roman concrete, as I’ve discussed in some of my other videos, was not poured like modern 41 00:03:11,379 --> 00:03:14,209 concrete, but spread in courses. 42 00:03:14,209 --> 00:03:20,550 First, retaining walls of brick or stone were constructed as a sort of form. 43 00:03:20,550 --> 00:03:26,150 A layer of coarse aggregate – in the Colosseum’s case, chunks of basalt and tufa – was laid 44 00:03:26,150 --> 00:03:33,310 down between these walls, and pozzolana mortar was troweled over the rubble bed, almost dry. 45 00:03:33,310 --> 00:03:37,620 The mixture was then pounded firm with wooden mallets. 46 00:03:37,620 --> 00:03:43,640 Besides its strength and durability, Roman concrete had the great virtue of being cheap. 47 00:03:43,639 --> 00:03:48,529 All the materials were available locally; and – unlike masonry – a large concrete 48 00:03:48,530 --> 00:03:52,949 structure could be built largely with unskilled labor. 49 00:03:52,949 --> 00:03:59,089 By my best estimate, the upper and lower foundations together used roughly 250,000 cubic meters 50 00:03:59,090 --> 00:04:01,489 of rubble and concrete. 51 00:04:01,489 --> 00:04:06,110 Again following Janet DeLaine, who wrote an article on the relative costs of different 52 00:04:06,110 --> 00:04:11,360 types of Roman construction, I estimate that each cubic meter of concrete cost the equivalent 53 00:04:11,360 --> 00:04:14,340 of 10 days’ wages for a laborer. 54 00:04:14,340 --> 00:04:20,220 By our equation, that gives a total of about 10,000,000 sestertii for the foundation. 55 00:04:20,220 --> 00:04:24,050 Next, work began on the superstructure. 56 00:04:24,050 --> 00:04:28,520 Although most large Roman buildings were made of brick-faced concrete, both the perimeter 57 00:04:28,519 --> 00:04:33,069 wall and the interior support columns of the Colosseum were built with massive blocks of 58 00:04:33,069 --> 00:04:37,939 travertine, quarried at Tivoli and ferried to Rome by barge. 59 00:04:37,939 --> 00:04:42,379 The Colosseum required about 100,000 cubic meters of travertine – roughly one-fiftieth, 60 00:04:42,379 --> 00:04:47,649 incidentally, of all the travertine ever quarried by the Romans. 61 00:04:47,649 --> 00:04:52,679 The stone, cut into blocks with an average weight of four tons, was lifted into place 62 00:04:52,680 --> 00:04:57,810 by simple treadwheel cranes like the one pictured in this relief, and clamped with 300 tons 63 00:04:57,810 --> 00:05:00,199 of iron. 64 00:05:00,199 --> 00:05:04,830 Travertine is a hard and heavy stone, difficult to work and transport. 65 00:05:04,829 --> 00:05:07,959 It was correspondingly expensive. 66 00:05:07,959 --> 00:05:12,750 Each cubic meter, by DeLaine’s estimate, cost the equivalent of 100 days’ wages for 67 00:05:12,750 --> 00:05:14,370 a laborer. 68 00:05:14,370 --> 00:05:18,530 The basic cost would have been amplified by the fact that each block had to be lifted, 69 00:05:18,529 --> 00:05:22,549 sometimes as much as 50 meters, by muscle power. 70 00:05:22,550 --> 00:05:25,699 Iron was also much more expensive than it is now. 71 00:05:25,699 --> 00:05:31,129 So let’s say that building the travertine components of the Colosseum cost 50,000,000 72 00:05:31,129 --> 00:05:32,509 sestertii. 73 00:05:32,509 --> 00:05:36,370 Although the key structural elements of the Colosseum were travertine, the vaults and 74 00:05:36,370 --> 00:05:43,180 substructures under the seats used roughly 100,000 cubic meters of tufa and concrete. 75 00:05:43,180 --> 00:05:49,040 Tufa – a soft volcanic stone – was considerably less expensive than travertine, and concrete, 76 00:05:49,040 --> 00:05:51,540 as we’ve seen, was cheaper still. 77 00:05:51,540 --> 00:05:56,919 The relative economy of the materials, however, was partially offset by the complexity of 78 00:05:56,918 --> 00:06:01,529 constructing so many vaults, ramps, and passageways. 79 00:06:01,529 --> 00:06:06,899 So I think that 20,000,000 sestertii is a reasonable guess for the cost of the substructures 80 00:06:06,899 --> 00:06:09,339 and passageways. 81 00:06:09,339 --> 00:06:14,388 Except for the uppermost tier, which had wooden benches, the seats of the Colosseum were made 82 00:06:14,389 --> 00:06:16,120 of Carrara marble. 83 00:06:16,120 --> 00:06:20,478 Although this was one of the least expensive varieties of marble, it still cost far more 84 00:06:20,478 --> 00:06:26,180 than travertine, perhaps the equivalent of 150 laborer-days per cubic meter. 85 00:06:26,180 --> 00:06:31,410 I’ve never seen any estimate for the amount of marble used in the Colosseum. 86 00:06:31,410 --> 00:06:37,229 The lowest tier of seats, the Senatorial podium, was built entirely of marble; the seats above 87 00:06:37,228 --> 00:06:41,199 had brick substructures faced with marble slabs. 88 00:06:41,199 --> 00:06:47,569 On that basis, I’ll say, more or less arbitrarily, that 5,000 cubic meters of marble were used 89 00:06:47,569 --> 00:06:49,480 throughout the building. 90 00:06:49,480 --> 00:06:53,560 If that number is anything like correct, the cost of the marble would have been around 91 00:06:53,560 --> 00:06:55,788 3,000,000 sestertii. 92 00:06:55,788 --> 00:07:00,459 The corridors of the Colosseum were plastered, painted, and equipped with lead pipes for 93 00:07:00,459 --> 00:07:01,788 water fountains. 94 00:07:01,788 --> 00:07:07,469 More than 150 life-size statues stood in the arches of the upper stories, and imposing 95 00:07:07,470 --> 00:07:11,050 quadriga groups crowned the main entrances. 96 00:07:11,050 --> 00:07:15,670 The statues alone, to judge from attested prices, would have collectively cost well 97 00:07:15,670 --> 00:07:18,050 over a million sestertii. 98 00:07:18,050 --> 00:07:22,310 Without attempting to estimate the expense of each component, I think it’s reasonable 99 00:07:22,310 --> 00:07:27,819 to suggest total finishing costs in the neighborhood of 2,500,000 sestertii. 100 00:07:27,819 --> 00:07:32,430 So: how much did it cost to build the Colosseum 19 centuries ago? 101 00:07:32,430 --> 00:07:37,168 Adding up the estimates I’ve given to this point brings us to 86,000,000 sestertii. 102 00:07:37,168 --> 00:07:43,359 This, I suspect, is still too low, since basic estimates on the basis of material fail to 103 00:07:43,360 --> 00:07:48,610 account for the many challenges of constructing a building on the Colosseum’s scale. 104 00:07:48,610 --> 00:07:52,639 So let’s say, just to have a nice round figure we can work with, that construction 105 00:07:52,639 --> 00:07:57,410 cost something on the order of 100,000,000 sestertii. 106 00:07:57,410 --> 00:07:59,210 This was a lot of money. 107 00:07:59,209 --> 00:08:04,649 The average annual income for a Roman laborer was around 1,000 sestertii. 108 00:08:04,649 --> 00:08:09,519 Imperial Roman senators, who were required to own property worth at least 1,000,000 sestertii, 109 00:08:09,519 --> 00:08:11,740 were very wealthy men. 110 00:08:11,740 --> 00:08:16,960 The two richest Romans known to us were worth 400,000,000 sestertii – four times the estimated 111 00:08:16,959 --> 00:08:19,629 cost of the Colosseum. 112 00:08:19,629 --> 00:08:24,519 But if my estimate is anything like correct, the Colosseum was far from the most expensive 113 00:08:24,519 --> 00:08:26,740 building project in Rome. 114 00:08:26,740 --> 00:08:31,519 Domitian reportedly spent nearly 300 million sestertii just gilding the roof and doors 115 00:08:31,519 --> 00:08:35,210 of the vast Temple of Jupiter on the Capitoline Hill. 116 00:08:35,210 --> 00:08:40,060 And the Aqua Claudia and Aqua Anio Novus, the two greatest aqueducts of the imperial 117 00:08:40,059 --> 00:08:44,439 city, cost 350,000,000 sestertii to complete. 118 00:08:44,440 --> 00:08:49,529 Even these were dwarfed by the Forum of Trajan, whose cost may have approached a billion sestertii. 119 00:08:49,528 --> 00:08:55,509 It is impossible to convert Roman sestertii to a modern currency with any accuracy. 120 00:08:55,509 --> 00:09:01,350 But if we assume, on the basis of comparative prices, that an early imperial sestertius 121 00:09:01,350 --> 00:09:05,490 had the purchasing power of about twenty dollars, the Colosseum cost the ancient equivalent 122 00:09:05,490 --> 00:09:12,470 of $2,000,000,000 – about as much, in other words, as a very expensive modern stadium. 123 00:09:12,470 --> 00:09:17,750 Now it’s time to tackle our second question: how much would it cost to build an exact replica 124 00:09:17,750 --> 00:09:18,958 of the Colosseum? 125 00:09:18,958 --> 00:09:25,119 Initially, I thought about trying to estimate the cost of doing everything – from quarrying 126 00:09:25,120 --> 00:09:30,629 the stones to laying the concrete – the same way it was done 19 centuries ago. 127 00:09:30,629 --> 00:09:37,740 This, however, proved impossible, since most ancient tools and techniques no longer exist. 128 00:09:37,740 --> 00:09:43,549 Speaking only of transport, for example, you’d need to build hundreds of heavy wooden carts, 129 00:09:43,549 --> 00:09:50,139 purchase and maintain a herd of oxen to draw them, and train a battalion of ox-drivers. 130 00:09:50,139 --> 00:09:54,720 And if the work were done entirely by artisans using hand tools – many of whom would have 131 00:09:54,720 --> 00:09:59,940 to be specially trained – the cost of labor alone would be astronomical. 132 00:09:59,940 --> 00:10:05,130 So I decided instead to estimate the cost of building a replica of the Colosseum made 133 00:10:05,129 --> 00:10:10,019 with the original materials but using modern machines and construction methods. 134 00:10:10,019 --> 00:10:16,539 The site, I decided, would be in America, on a plot of land already owned by the builder, 135 00:10:16,539 --> 00:10:22,569 and in an area with easy access to both a large labor pool and the raw materials. 136 00:10:22,570 --> 00:10:26,820 I did not specify the region in which the replica would be built, or whether construction 137 00:10:26,820 --> 00:10:30,320 would be done by unionized workers. 138 00:10:30,320 --> 00:10:33,000 Then I tried to find an expert who could help me. 139 00:10:33,000 --> 00:10:39,330 I emailed several classicists, a half-dozen professors of civil engineering, the International 140 00:10:39,330 --> 00:10:45,330 Union of Bricklayers and Allied Craftworkers, and a limestone quarry in Indiana, among many 141 00:10:45,330 --> 00:10:46,330 others. 142 00:10:46,330 --> 00:10:48,000 Nobody responded. 143 00:10:48,000 --> 00:10:55,049 Finally, I put up a community post here on YouTube, asking anyone with experience estimating 144 00:10:55,049 --> 00:10:59,088 the costs of large masonry structures to send me a message. 145 00:10:59,089 --> 00:11:05,870 To my profound relief, several subscribers heroically volunteered to undertake the task. 146 00:11:05,870 --> 00:11:10,289 The first of the three detailed estimates I received was submitted by a subscriber with 147 00:11:10,289 --> 00:11:15,028 the username Magnificus, an architectural project manager. 148 00:11:15,028 --> 00:11:20,088 With the use of Computer Aided Design and estimating software, he proceeded level by 149 00:11:20,089 --> 00:11:23,430 level, expensing by material and finishes. 150 00:11:23,429 --> 00:11:29,469 Thus he assessed the cost of the senatorial podium, with its lavish use of marble, at 151 00:11:29,470 --> 00:11:34,430 nearly $27,000,000, but assigned the uppermost tier of seating – with its wooden benches 152 00:11:34,429 --> 00:11:37,829 – a cost of only $3,500,000. 153 00:11:37,830 --> 00:11:44,120 He believed that the 160 marble statues perched in the upper arcades could be made for a cool 154 00:11:44,120 --> 00:11:48,750 $4,000,000 with CNC stone carving machines. 155 00:11:48,750 --> 00:11:54,919 The entire Colosseum, he estimated, could be replicated for as little as $150,000,000. 156 00:11:54,919 --> 00:12:00,669 This, he acknowledged, seemed low, but he pointed out that the Colosseum had no modern 157 00:12:00,669 --> 00:12:05,319 amenities, was made from materials that could be easily sourced, and was decorated in a 158 00:12:05,320 --> 00:12:09,019 relatively straightforward and repetitive manner. 159 00:12:09,019 --> 00:12:13,509 The next estimate was submitted by Tim Wilkinson, an engineer. 160 00:12:13,509 --> 00:12:19,429 In his experience, reinforced concrete for a high-rise structure costs about $1,500 per 161 00:12:19,429 --> 00:12:20,649 cubic yard. 162 00:12:20,649 --> 00:12:25,809 Applying this metric to the Colosseum would give a figure of $450,000,000 for the foundations 163 00:12:25,809 --> 00:12:29,969 alone, though Tim thinks that the actual expense would be much lower, thanks to economies of 164 00:12:29,970 --> 00:12:31,000 scale. 165 00:12:31,000 --> 00:12:35,929 Still, when factoring in the huge quantities of material needed for the seating bowl and 166 00:12:35,929 --> 00:12:41,419 circuit wall, he believes that the total cost of a replica built with the best modern materials 167 00:12:41,419 --> 00:12:44,429 would exceed a billion dollars. 168 00:12:44,429 --> 00:12:50,229 The last and most detailed estimate was submitted by Jim Williams, a retired architect with 169 00:12:50,230 --> 00:12:52,379 a background in engineering. 170 00:12:52,379 --> 00:12:59,549 Jim estimated total material costs of about $400,000,000, including $250,000,000 of travertine 171 00:12:59,549 --> 00:13:02,870 and $100,000,000 of marble. 172 00:13:02,870 --> 00:13:08,959 The equipment required – 20 bulldozers, 10 concrete pumps, and a total of 30 cranes 173 00:13:08,958 --> 00:13:12,549 – would cost about $25,000,000. 174 00:13:12,549 --> 00:13:20,189 About 1100 workers would be needed, including 75 skilled stone carvers and 40 fresco artists. 175 00:13:20,190 --> 00:13:25,800 Assuming a two-year construction time, labor costs would be just under $450,000,000. 176 00:13:25,799 --> 00:13:30,669 Once construction management costs, permit fees, and all other expenses were accounted 177 00:13:30,669 --> 00:13:35,519 for, the total price tag would be just under a billion dollars. 178 00:13:35,519 --> 00:13:39,649 Since I lack the expertise to assess these estimates in any meaningful way, I’m most 179 00:13:39,649 --> 00:13:44,299 intrigued by the differences between them, which reflect the fact that there is no single 180 00:13:44,299 --> 00:13:49,799 answer to the question of how much it would cost to build a replica of the Colosseum. 181 00:13:49,799 --> 00:13:53,889 The only way to answer the question would be to actually build a replica – and even 182 00:13:53,889 --> 00:13:59,690 then, you’d only have one possible answer, contingent on a unique set of local circumstances. 183 00:13:59,690 --> 00:14:05,720 In the first part of this video, I estimated that the original Colosseum cost something 184 00:14:05,720 --> 00:14:11,399 like 100,000,000 sestertii, which I equated – more or less arbitrarily – with $2,000,000,000. 185 00:14:11,399 --> 00:14:18,350 If, as it seems, the cost of producing a modern replica would be half that figure, or even 186 00:14:18,350 --> 00:14:23,350 less, the difference is a testimony to modern construction technology, whose efficiencies 187 00:14:23,350 --> 00:14:28,019 counterbalance the vastly higher costs of modern labor. 188 00:14:28,019 --> 00:14:33,730 I won’t pretend that the figures thrown around in this video have any real validity. 189 00:14:33,730 --> 00:14:38,680 These are estimates piled on assumptions, the turrets and battlements of a castle in 190 00:14:38,679 --> 00:14:40,219 the air. 191 00:14:40,220 --> 00:14:44,710 But the exercise is intriguing in itself, and hopefully illuminates something about 192 00:14:44,710 --> 00:14:49,730 the ways and means of building an ancient wonder. 193 00:14:49,730 --> 00:14:54,589 If you enjoyed this video, please consider supporting toldinstone on Patreon. 194 00:14:54,589 --> 00:15:00,920 You might also enjoy my book, Naked Statues, Fat Gladiators, and War Elephants. 195 00:15:00,919 --> 00:15:06,528 A special thanks to Magnificus, Tim Wilkinson, and Jim Williams; and thanks to all of you 196 00:15:06,528 --> 00:15:07,200 for watching.