The cathedral of a controversial, conservative, schismatic sect that declared the Catholic Church heretical and founded its own succession of popes.

This natural monument has an origin story steeped in legend.

A mountain cave is the site of archaeological findings and Paleolithic rock art.

Inside a state forest, the forgotten remains of a Cold War defensive installation.

An abandoned village, frozen in time by the threat of a landslide.

This scenic fortress dates back at least 2,400 years to the time of Magna Graecia.

A colossal aqueduct from the second century B.C., deeply hidden in a gorge on the outskirts of Rome.

A secluded fortress from the days of the Crusades that offers breathtaking views.

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

Accessible only by train, the beauty of Agawa Canyon Wilderness Park is worth the journey.

A schooner, nicknamed "The Unsinkable," with a long history of survival in the Indian Ocean.

The ruins of this medieval castle overlook the lake of Piediluco in what was once a sacred forest.

One of the few places in the world home to living stromatolites.

The only visible remains of this ancient Greek underground temple is its roof protruding from the earth.

An off-the-beaten path cave with an underground lake.

A striped 12th-century basilica sits in the countryside of Sardinia.

Once a bridge over the River Begej, now high and dry.

A narrow opening between the mountains of the Amalfi Coast creates a scenic hidden beach.

Unscathed for almost 2,000 years, the best preserved Roman triumphal arch is in a small southern Italian city.

This medieval mountain town is also known as the "Village of Streams."

The ruins of a 12th-century Cistercian monastery can be found alongside World War II tank traps and pillboxes.

According to the legend, this structure was built in a single night with the help of the devil.

An abandoned monastery sits on a far-off island in the Adriatic Sea.

A prison tower–like edifice honoring a beloved local benefactor.