Colosseum (Partial Elevation) Rome — completed 216CE Within a precinct of 337 by 328 metres, the Baths of Caracalla align the natatio, frigidarium, tepidarium and a domed caldarium some 35 metres across on a single axis, mirrored on either side, above two kilometres of service galleries. Inaugurated in 216 and built by an estimated average of 7,000 men, they worked until the Goths cut the water in 537, and their great hall later served as the model for New York's Pennsylvania Station. Re-traced by hand as a worm's-eye axonometric, the sheet reads them from below: the plan at the base, and above it the vaults the walls were built to carry. Architect unknown.