Grotta di Cocceio

[1] It was burrowed through the tuff stone of Monte Grillo by the architect Lucius Cocceius Auctus at the command of Agrippa who was in the process of converting the Lake into a military port, the Portus Julius.

The Avernus side of the passage was decorated with a colonnade and had many statues in niches hewn into the tuff walls of the entrance.

Light and air were provided by six vertical shafts dug into the hill (the longest of which was over thirty metres high) The Aqua Augusta aqueduct supplying the port was dug in a tunnel parallel to and on the northern side the road and was also equipped with niches and vertical shafts.

The Grotta was heavily damaged during World War II and is no longer open to the public.

However, colonies of five species of legally-protected bats were discovered during the restoration, making an environmental assessment necessary before the reopening can go through.