The Colosseum, also known as the Flavian Amphitheater, is an immense oval structure 189 meters long, 156 meters wide and 48 meters high, with an elliptical perimeter spanning 524 meters. The construction of this colossal building was carried out with the participation of several groups of workers during the day and was based on the use of prefabricated components that allowed for modular construction. For this reason, this monument is considered to have served as a model for modern sports venues, thanks to its ingenious design that provides solutions to contemporary challenges.

The building's architecture is supported by a series of arches that surround the first three levels of the Colosseum. Here, the typical Roman aesthetic is evident, with round arches rising on sturdy pillars that also act as supports for decorative columns. These pillars support the architraves, friezes and cornices that delimit each of the first three floors.

The interior of the Colosseum is its greatest treasure: the tiers (or cavea) extend over numerous staggered rows resting on travertine pilasters, rather than taking advantage of the natural slopes of the terrain. This arrangement creates an intricate system of vaulted aisles and stairways, designed to ensure the smooth flow of large crowds. Both barrel vaulting and groin vaulting were used in its design, the latter of greater complexity.

The facade of the Colosseum rises on a stylobate that serves as the base for the four upper levels. The second floor has 80 arcades in Tuscan Doric style, which convey a sense of solidity and robustness. The second floor, in Ionic style, has a base, a more slender shaft than the Doric order and a capital decorated with volutes. The third floor follows the composite style, with capitals ornamented with acanthus leaves. The fourth and last floor incorporates a massive attic, adorned with Corinthian style columns. This level served several functions, such as increasing the capacity of the Colosseum, providing more space inside and improving its visual appearance. On this level, 240 wooden poles supporting a large canopy were installed.

Inside the Colosseum, statues were placed between the spaces between the columns of the second and third floors, while the aisles of the stands featured marble and stucco reliefs.

The grandstand surrounds the arena and underneath it is a sub-floor designed to speed up the shows. By means of a system of elevators, the beasts were taken to the arena, and there were corridors, stairways and a careful distribution of rooms and chambers. In addition, a water conduction system was implemented to turn the arena into a large pool for the naumachias.