Packed with geological formations, an ancient river, and taxidermied seals, this overlooked coastal cave system is worth a spelunk.

Europe's only Temple of Mithras located in a natural cave.

This Roman theater was crafted into the local tuff rock and was rediscovered during the 19th-century.

Knights Templar are visible inside this stunning Cistercian abbey.

One of the four sanctuaries of Rieti's Holy Valley was the site of the first living nativity scene.

The hilltop town of Segni was once home to an ancient Roman colony and garrison.

An impressive bridge over a ravine also served as an aqueduct.

After World War II, this former concentration camp in Northern Italy became a refuge for those displaced by the war.

A rare example of an octagonal Catholic church.

The sacristy of this church contains remains and relics of members of the Aragonese royal family.

This incredible second-century sculpture depicts a trio of gods worshipped by the ancient Romans.

Before the more famous Royal Palace of Caserta, the king of Naples first commissioned this overlooked residence.

A monk spent 14 years carving steps through tuff to make this religious site more accessible to pilgrims.

This seventh-century fortification marked the western border of the Lombard duchy of Spoleto.

The walls of this tiny Italian church are entirely covered with frescoes.

These ruins of a Phoenician sanctuary in Sicily have a dark history.

Magnificent frescoes decorate the interior of this Romanesque church, which also showcases an unusual phenomenon during winter solstice.

The ruins of this medieval castle now stand as a monument against all wars.

Its look is severe, but its location, isolated on a hill in the middle of the countryside, is particularly scenic.

In this nearly 1,000-year-old monastery, monks painstakingly restore old books.

You can only access this hermitage by crawling under a ledge suspended above an overhang.

This trail was once used to smuggle cigarettes, sugar, and other black market goods between Italy and Switzerland.

When occupying Nazi troops detonated a mine below, medieval frescoes were revealed in this small cliff-side hermitage.

This small Roman arch was transformed into a dwelling by the founder of the Trinitarian Order.