Between 1928 and 1932, two enormous wooden ships, which once belonged to the Emperor Caligula, and had lain on the bottom of the Lake Nemi for over nineteen hundred years, were salvaged in what was perhaps the greatest underwater archaeological recovery ever accomplished.

The larger ship was essentially an elaborate floating palace, which contained quantities of marble, mosaic floors, heating and plumbing such as baths among its amenities. Both ships featured technology long thought to be recent inventions.