Ostia Antica, once the bustling port city of ancient Rome, was established around the 4th century BC at the mouth of the River Tiber. It served as the primary harbor for Rome and became a major center of commerce, trade, and cultural activity, connecting Rome to the Mediterranean. The city flourished for centuries, with significant expansion during the reign of Emperor Augustus and subsequent emperors who further developed its infrastructure, including baths, temples, and residential complexes.

The city of Ostia reflects a rich blend of Roman architecture and culture. Visitors can explore the ancient ruins that include the well-preserved theater, which could hold up to 4,000 spectators, and the Forum, which was the administrative and religious heart of the city. The public baths, such as the Baths of Neptune, feature stunning mosaics depicting marine deities and mythological scenes. The site also has a number of temples, including the Temple of Hercules, and many multi-story apartment buildings called 'insulae,' offering a glimpse into the lives of ordinary Roman citizens.

One notable feature is the Piazza of the Corporations, located behind the theater. This area served as the headquarters for various trade guilds that controlled commerce within the port. The mosaics on the floor of each office depict the type of goods that were traded, ranging from grain to exotic animals, highlighting Ostia's role as a commercial hub. The archaeological park also features the Necropolis of Porto and other burial sites, which offer insight into the funerary practices of the time.

Ostia Antica is easily accessible via train from Rome, making it a popular day trip destination. The site provides a vivid representation of Roman urban life, similar to Pompeii, but with fewer crowds, making it a fascinating place to explore ancient Roman history.