The most famous and important monument, and the starting and ending point of every sightseeing tour, is the amphitheater, popularly known as the Arena of Pula, which was once the site of gladiatorial combats. It was built in the 1st century AD during the reign of Emperor Vespasian, at the same time as the magnificent Colosseum in Rome.

The amphitheater has an elliptical ground plan, with the longer axis measuring approximately 130 meters and the shorter one approximately 100 meters. Gladiator fights took place in the central, flat area known as the arena, while spectators could sit in the stone tiers or stand in the gallery. It is believed that the amphitheater could accommodate around 20,000 spectators. Local limestone was used in its construction. In the Middle Ages, it hosted jousting tournaments and fairs. Today, it serves as a venue for summer performances—film festivals, opera seasons, equestrian events, and concerts—with a capacity of approximately 5,000 spectators.

The underground passages, once used by gladiators, now regularly host an exhibition about wine and olive cultivation in Istria in antiquity. The exhibits include reconstructions of machines once used to produce olive oil and wine (mills, presses, vessels) and amphorae used for storing and transporting these products.