The theatre fell out of use in the early 4th century and the structure served as a quarry, e.g., the Pons Cestius in 370 AD. However, the statues located inside the building were restored by Petronius Maximus in 421 and the remaining structure still housed small residential buildings. In the Early Middle Ages the theatre was used as a fortress of the Fabii and then at the end of the 11th century (when it was known as templum Marcelli), by Pier Leoni and later his heirs (the Pierleoni).