File:EB1911 Rome - Example of Construction.jpg

English: An example of ancient Roman use of materials in construction. Some details of the Colosseum (upper part of one of the inner radiating walls under the cunei) are examined. A, A. Marble seats on brick and concrete core, supported on vault made of pumice-stone concrete (C). B. Travertine arch at end of raking vault (C). D. One of the travertine piers built in flush with the tufa wall to give it extra strength. E, E. Wall of tufa concrete faced with triangular bricks, carrying the vaults of pumice concrete which support the marble seats. F. Travertine pier at end of radiating wall. G. Brick-faced arch of concrete to carry floor of passage. H, H. Tufa wall, opus quadratum. J, J, J. Line of steps in next bay. K, K. Surface arches of brick, too shallow to be of any constructional use, and not meant for ornament, as the whole was stuccoed; they only face the wall (which is about 4 ft. thick) to the average depth of 4 in.