The building, which fell into ruin during the barbarian invasions, served for centuries as a quarry for building materials: it's no coincidence that during the Middle Ages it was known as "grotte" (caves). In particular, it was stripped of its entire cladding and all its columns. Later, houses and buildings began to be built on the remaining ruins, using the remaining structures of the Amphitheater to perfectly preserve its shape.
L'current splendid square, singular and unique in its kind, was built by the architect Nottolini (from 1830) who had some buildings in the centre demolished and created the street called the Amphitheatre around it.