Ostica Antica was Rome’s main harbor for more than 600 years until commercial competition brought the city into decline. The city was well preserved by silt. As far as the eye can see, the main street was the Decumanus Maximus and the ruins of the buildings were those of multi-story apartments complete with shops, baths, and bars on the ground floor. It was undoubtedly very cosmopolitan for its time.
The ruins also house a large temple and an amphitheater.
Overall, I felt the ruins were more fascinating than those of Pompeii. There was certainly more to see. At Pompeii, one was restricted to the areas that the attraction allowed.
The museum displayed various sculptures found during the excavation.
Tip: Ostia Antica is reachable via train from Rome. A metro ticket will suffice. The entire train ride lasts for about 30 minutes one-way. The fare may be subject to change.
Machiavelli, F., Martin, S., Townsend, H., & Tyrrell, N. (Eds.). (2014). Italy. New York, NY: DK Eyewitness Travel.