This is an artificial cave from Roman times, entirely covered in opus incertum of limestone with a barred vault. The Roman builders created the two spaces from the rocky embankment where once, it is thought, a waterfall flowed in prehistoric times, and where a small cave perhaps already esisted. Thus, a cool, pleasant room was created that looked onto the sheer precipice over the Aniene valley, with dramatic views.

Nymphaeum-viewpoint

Ponte Lupo Clearing In ancient times, in the Valley of Hell, the Aniene formed a small lake later named Pelago, of which only the traces remain; it gushed out into the Roman countryside. During the violent floods of 105 A.D., described by Pliny the Younger, the waters sank into a new underground tunnel (the Mermaids’ Grotto) creating the natural bridge known as Radura di Ponte Lupo, or the Ponto Lupo Clearing.

Stipa's cascade, known as Bernini's Cascade

The cascade is fed by the artificial Stipa canal which, in classical times, served the acqueduct of the Villa di Volpisco, and in medieval times fed the numerous mills that were built on the ruins of the villa. In 1669, the architect Luigi Bernini (the brother of Gian Lorenzo Bernini) renovated the artificial Stipa canal, and since then the waterfall has been known by that name.

Miollis's tunnel The Cave of Neptune can be reached through the Miollis, a tunnel in the heart of the rock, dug in 1809 by French General, the governor of Rome. To illuminate this path, Miollis created some holes-windows from which it's possible to observe the magnificent view and take external light.

Viewpoint over Valley of Hell