Not far from a popular beach, an unfinished, abandoned mansion for Bulgaria's last communist dictator.

Underneath this Byzantinian church lies a necropolis filled with ancient tombs and the ruins of previous churches.

A marvel of Byzantine engineering under the streets of Istanbul.

A sixth-century Byzantine cistern hidden below a modern carpet store.

Crossing a suspension bridge above a forest is the only way to reach this 12th-century monastery.

These natural cliffs look like they are a part of an old castle complex.

Outstanding, eerie frescoes and decorations fill this 19th-century monastery.

The second-largest Jewish temple in Bulgaria was deserted after World War II, seized by the communist government and then abandoned again.

A collection of art from Bulgaria's time as a communist state.

A cemetery with goat-horn bedecked gravestones.

This oddly shaped building is a surprising Soviet-era crematorium.

This 1000 year old relic-filled cave monastery and UNESCO World Heritage Site also hosts an amazing micro-miniature museum.

The deepest metro station in the world.

An Art Nouveau building covered in animal gargoyles and grotesques.

340-foot statue built to honour the Heroes of the Soviet Union.

This unassuming museum's slogan translates to “there is a limit of sadness, anxiety has no limits."

The last standing example of an ancient district's teatime tradition.

A collection of old neon signs from all over Poland line a secluded courtyard.

This hidden collection of everyday objects illustrates life within communist Poland.

The mummified relic of St. Catherine sits forever on a golden throne.

World's largest crossword puzzle spans the side of a towerblock, its clues scattered throughout the city.

A submerged archeological park still holds the wonders of a Roman Sodom.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

This Ukraine alleyway has become its own little island of forgotten things.