Theatre of Marcellus is an ancient Roman theatre located in Rome, Italy. Built between 13 and 11 BCE, it was commissioned by Julius Caesar and completed by Augustus in honor of his nephew, Marcellus. The theatre could accommodate around 20,000 spectators and featured a semi-circular design typical of Roman architecture. The structure is notable for its impressive use of arches and columns, showcasing the Corinthian style. Although much of the original theatre has been lost over time, parts of it still stand today, and it has influenced the design of later theatres throughout history.