What architectural feature served as a public square or marketplace in a Roman city?

The forum was a central feature in Roman cities, serving as the primary public square or marketplace. It functioned as the heart of civic life, where citizens gathered for various activities such as commerce, political discussions, social events, and religious practices. The design of a forum typically included open spaces surrounded by important public buildings, including basilicas (used for legal and other public proceedings), temples (for worship), and other civic structures, creating a focal point for community interaction and governance.

In contrast, other options like the basilica and temple served specific functions: basilicas were primarily for legal proceedings and gatherings, while temples were dedicated to housing deities and conducting religious ceremonies. The amphitheater, on the other hand, was meant for entertainment purposes, particularly for spectacles such as gladiatorial contests and theatrical performances. Thus, the forum distinctly encapsulated both the marketplace and the communal hub of Roman social and political life.