The Colosseum is a huge amphitheater. It was designed for gladiatorial contests and combats between men and animals, or simply between animals. The exterior is made up of rows of arches knows as arcades. There are three stories of round arches framed by entablatures and engaged columns. There are three types of columns used in the Colosseum. On the ground floor there are Tuscan columns, on the second-floor Ionic, and on the third Corinthian. Small windows and engaged rectangular Corinthian pilasters are located on the fourth floor. The Roman’s intentionally put the heaviest (Doric) columns on the lower level, building up with more delicate structures. The surface of the outer wall becomes flatter as the structure rises, carrying the viewer’s eye upward. The repeated round arches lead the eye along the entirety of the building.
Two types of vaults were used in the ceilings of the corridors. The upper wall contained sockets so that poles could be inserted to support canvas that covered the structure and protected spectators from sun and rain. It contained a built-in drainage system used for washing away the blood and gore of combat and animals.
Travertine, a hard, durable limestone that mellows to a golden yellow, was used for the framework of the piers, and tufa and brick-faced concrete were used for the walls between the piers. There was marble on the interior as decorative facing. However, for the large part concrete was used, a rough mixture of mortar, gravel, rubble, and water.
The inner part of the colosseum is circular, with step like seating. The circular shape creates fluidity and harmony. The seating allowed for all the spectators to view the gruesome entertainment. A series of stairs below the ‘bleachers’ allowed for viewers to climb to the top of the building. The center was comprised of an enormous pit, where the entertainment would take place. Directly below the pit there were cages and a series of passageways, which added to the drama of entering the ‘stage.’