We stumbled onto ostia antica and it became our favorite rome day entire ancient roman port city incredibly preserved but somehow gets no tourist traffic

Take regional train from roma porta san paolo pyramide fl1 line 150 euros each way 35 minutes to ostia antica station site entry 12 euros covers massive area with amphitheater baths mosaics apartment buildings where regular romans lived

We spent 5 hours wandering roman streets and theaters without seeing single tour group you can climb on structures explore at own pace neptune baths mosaics are stunning

Bring lunch and water limited food on site the peace and ability to absorb history without crowds made this more memorable than colosseum for us honestly