In Republican Times Ostia was Rome’s main commercial port and military base defending the coastline and the mouth of the Tiber. It’s decline began in the 4th century, when a reduction in trade was combined with the gradual silting up of the harbour and when malaria became endemic in this area. Buried for centuries by sand, the city is remarkably well preserved and still today we can understand the layout of Ostias’s streets and the functions of the public buildings: bath houses with black-and white floor mosaics, the theatre, taverns and shops, the Forum, where officials met to discuss the city’s affairs, private apartments and a laundry and the firemen’s barracks. Ostia Antica was ranked amongst the top 100 most meaningful excavation sites in the world by UNESCO.