On the northeastern slopes of the central hill of the city, below the Castle are the remains of a Roman theater: in addition to the Amphitheater, Pula had two other theaters during the Roman period. The larger one, which has not been preserved, was situated outside the city, on the slopes of Zaro hill (Monte Zaro), south of the city walls. The other theater known as the Small Roman Theater was situated within the city walls. The remains of scene, semicircular orchestra and tired section for the audience have partly been reconstructed. Below the theater is the building of the one-time German Royal Gymnasium, which in 1930 became the Archaeological Museum of Istria. Today the museum displays a rich collection of prehistoric, classical and early medieval monuments found in Istria.
https://www.pulainfo.hr/where/small-roman-theater