Mount Nyiragongo has erupted at least 34 times since 1882 and is home to the world's largest lava lake.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

This Latvian shot factory is still used twice a year to manufacture bullets the old-fashioned way.

This enigmatic artifact remained buried in a churchyard for years.

A 300-kilogram egg sculpture that embodied a neighborhood revival.

A WWII museum that tries to reenact history.

An abandoned masterpiece of Soviet Brutalist architecture.

A fake Transylvanian castle houses a cathedral of antlers.

Budapest's Communist-era statues, banished to the suburbs.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Museum dedicated to the terror regimes of Hungary.

A Hungarian pharmacy museum with a box full of mummy powder.

Austria's very first and only nuclear power station was completed but never used.

This outsider art house has gone from clinical creation to astounding artwork.

This cubist Vienna church building looks like some sort of alien stonehenge.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

The solemn exterior conceals an opulent interior of this 17th century church.

This off-beat, quirky communism-themed bar isn't afraid to poke fun at its history.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.