This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

Deep in the Guatemalan jungle stands an ancient pyramid that once marked the reign of a king.

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

These ruins on Mont Tantané dates back to the Iron Age, but there is limited evidence for why a village was built so far from water or other resources.

A small town lost in the mountains of southern Italy hosts the childhood home of one of the most famous saints of the 20th century.

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

An 18th century fountain and two columns are all that remains of Rome's forgotten river harbor.

This grisly effigy displays an early Christian martyr who was skinned alive and beheaded.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

This breathtaking monastery was established by Saint Benedict himself 1,500 years ago.

A spiritual sanctuary in a natural cave.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Erotic art covers the walls of the largest ancient pleasure palace.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

Five candy-colored villages on the Italian Riviera.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Built by a king and rebuilt by an emperor, this aqueduct transported water for 1,200 years to this ancient Mediterranean hub.

The abandoned shell of what would have been the Jordanian royal family's summer palace.

An ancient tunnel in Jerusalem built to redirect water in the event of a siege is one of history’s great architectural innovations.

A Biblically notable site over the ruins of an ancient city that is now a protected World Heritage site.

The tallest waterfall in the Judean Desert is named for its connection to a biblical figure.