A church of bones, decorated with 40,000 human skeletons.

An enormous and lavish Gothic church in Czechia.

An ancient church on a tiny island covered in stone bible stories has controversially been turned into a museum.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

A Turkish ghost town abandoned in a population exchange with Greece.

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

This arch granting triumphal entrance into Antalya was designed to honor the emperor's visit.

A mesmerizing landscape of 18th-century cellars carved out of the land.

This architecturally eclectic fortress witnessed centuries of bloody turmoil, including the massacre of its ruling clan.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

A striking symbol of the Bulgarian capital.

Sofia's legislative center is continuously reinventing itself.

"Holy Wisdom" overlooks the city that became its namesake.

A vast Communist-era exhibition space in the Bulgarian capital.

An homage to the medieval rulers of Bulgaria.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

This historic black and white monastery is one of Bulgaria's architectural jewels.

The giant statue and its model solar system honor the native Pole who declared that the Earth revolves around the Sun.

What was once an underground Nazi city is now Europe's largest bat reserve.