Portus, Italy

Thirty kilometers southwest of Rome lies what may be ancient Rome's greatest engineering achievement: Portus. Built in the first century A.D., Portus was Rome's principal maritime harbor, replacing the port city of Ostia on the Tiber River (circled area) that had become inadequate to handle the hundreds of ships loaded with food stuffs to feed Rome's 1 million+ inhabitants. The hexagonal Trajanic Basin and the outer Claudian Basin (now silted up) formed a port complex without equal. In 2000 years, the coastline has moved seaward, and the Trajanic Basin is now a private lake. The image was acquired June 29, 2014, covers an area of 10 by 10 km, and is located at 41.7 degrees north, 12.3 degrees east.

http://photojournal.jpl.nasa.gov/catalog/PIA19209