The Amphitheatrum Castrense is a Roman amphitheatre next to the church of Santa Croce in Gerusalemme. It is dated to the first decades of the 3rd century AD. It was part of an Imperial villa complex which was built by emperors of the Severan dynasty. The open arches of the outer walls were walled up when the building was incorporated into the Aurelian Walls (271-275 AD), at which point it stopped being used for spectacles and began to be used as fortification, and the ground level around the building was lowered.
In the middle of the 16th century the remains of the second story were demolished for defensive needs. In the 18th century, a Hypogeum was found beneath the arena, filled with the bones of large animals. This leads researchers to believe that the spectacles here included Venationes, the hunting and killing of wild animals. Palladio and Étienne Dupérac made drawings about the ruins.
The building is a regular ellipse 88 meters long and 75.80 meters wide. It is constructed out of brick-faced concrete, with a few decorative elements in travertine. The structure was three stories high but only a section of the lowest story is preserved.References:
The Amphitheatre of the Three Gauls was part of the federal sanctuary of the three Gauls dedicated to the cult of Rome and Augustus celebrated by the 60 Gallic tribes when they gathered at Lugdunum (Lyon). The amphitheatre was built at the foot of the La Croix-Rousse hill at what was then the confluence of the Rhône and Saône.
Excavations have revealed a basement of three elliptical walls linked by cross-walls and a channel surrounding the oval central arena. The arena was slightly sloped, with the building"s south part supported by a now-vanished vault. The arena"s dimensions are 67,6m by 42m. This phase of the amphitheatre housed games which accompanied the imperial cult, with its low capacity (1,800 seats) being enough for delegations from the 60 Gallic tribes.
The amphitheatre was expanded at the start of the 2nd century. Two galleries were added around the old amphitheatre, raising its width from 25 metres to 105 metres and its capacity to about 20,000 seats. In so doing it made it a building open to the whole population of Lugdunum and its environs.