Architectural Physical description
The exterior of the Colosseum, showing the partially intact outer wall (left) and the mostly intact inner wall (right)
Original façade of the Colosseum
Entrance LII of the Colosseum, with Roman numerals still visible
Cross-section from the Lexikon der gesamten Technik (1904)
This painting by Giovanni Paolo Panini depicts a fanciful reconstruction of the Colosseum. The Walters Art Museum.
Unlike earlier Greek theatres that were built into hillsides, the Colosseum is an entirely free-standing structure. It derives its basic exterior and interior architecture from that of two Roman theatres back to back. It is elliptical in plan and is 189 meters (615 ft / 640 Roman feet) long, and 156 meters (510 ft / 528 Roman feet) wide, with a base area of 6 acres (24,000 m2). The height of the outer wall is 48 meters (157 ft / 165 Roman feet). The perimeter originally measured 545 meters (1,788 ft / 1,835 Roman feet). The central arena is an oval 87 m (287 ft) long and 55 m (180 ft) wide, surrounded by a wall 5 m (15 ft) high, above which rose tiers of seating.
The outer wall is estimated to have required over 100,000 cubic meters (131,000 cu yd) of travertine stone which were set without mortar held together by 300 tons of iron clamps. However, it has suffered extensive damage over the centuries, with large segments having collapsed following earthquakes. The north side of the perimeter wall is still standing; the distinctive triangular brick wedges at each end are modern additions, having been constructed in the early 19th century to shore up the wall. The remainder of the present-day exterior of the Colosseum is in fact the original interior wall.
The surviving part of the outer wall's monumental façade comprises three stories of superimposed arcades surmounted by a podium on which stands a tall attic, both of which are pierced by windows interspersed at regular intervals. The arcades are framed by half-columns of the Tuscan, Ionic, and Corinthian orders, while the attic is decorated with Corinthian pilasters. Each of the arches in the second- and third-floor arcades framed statues, probably honoring divinities and other figures from Classical mythology.
Two hundred and forty mast corbels were positioned around the top of the attic. They originally supported a retractable awning, known as the velarium, that kept the sun and rain off spectators. This consisted of a canvas-covered, net-like structure made of ropes, with a hole in the center. It covered two-thirds of the arena, and sloped down towards the center to catch the wind and provide a breeze for the audience. Sailors, specially enlisted from the Roman naval headquarters at Misenum and housed in the nearby Castra Misenatium, were used to work the velarium.
The Colosseum's huge crowd capacity made it essential that the venue could be filled or evacuated quickly. Its architects adopted solutions very similar to those used in modern stadiums to deal with the same problem. The amphitheatre was ringed by eighty entrances at ground level, 76 of which were used by ordinary spectators. Each entrance and exit was numbered, as was each staircase. The northern main entrance was reserved for the Roman Emperor and his aides, whilst the other three axial entrances were most likely used by the elite. All four axial entrances were richly decorated with painted stucco reliefs, of which fragments survive. Many of the original outer entrances have disappeared with the collapse of the perimeter wall, but entrances XXIII (23) to LIV (54) still survive.
Spectators were given tickets in the form of numbered pottery shards, which directed them to the appropriate section and row. They accessed their seats via vomitoria (singular vomitorium), passageways that opened into a tier of seats from below or behind. These quickly dispersed people into their seats and, upon conclusion of the event or in an emergency evacuation, could permit their exit within only a few minutes. The name vomitoria derived from the Latin word for a rapid discharge, from which English derives the word vomit.