Grotta

The biggest cave system in the Arabian Peninsula is home to a rare variety of blind fish.

At the most northwestern point of the contiguous United States lies a trail leading through an ancient forest to stunning cliff-side vistas and massive oceanside caves.

A series of idealized caves carved to entertain guests.

These caves secretly held national treasures during World War II.

Chilly air billows out from the entrance of an abandoned mine on a steep hillside, providing a refuge for Ice Age fauna and flora.

This archaeological site built into a tuff outcrop is filled with rock dwellings, the ruins of a medieval castle, and a necropolis.

This network of roads is one of the most unique Etruscan creations ever discovered.

Located in the middle of public park, this cave built in the early 19th century houses an ancient stone sarcophagus.