The remains of an entire Roman city can be explored in this interactive museum.

This hidden art nouveau gem was designed by an architect in search of a national style.

Hungarian self-built castle.

This Hungarian stilt village is built in a lake that never freezes over due to the power plant that that uses it as a cooling pond.

A fake Transylvanian castle houses a cathedral of antlers.

Tucked away near more famous landmarks lies a statue meant to symbolize the confluence and continuing development of human culture.

Hungarian mummies in beautiful painted coffins.

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

Museum dedicated to the terror regimes of Hungary.

Once the home of a hermetic monk, this cave now houses a small church.

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

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

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

This beautifully verdant lagoon is tucked below a massive volcano in a crater atop a black pebble beach.

This mountaintop observatory is home to one of the world's largest reflective telescopes.

This remarkable prehistoric town is full of watchtowers and houses that have withstood thousands of years.

According to the Guanches, the aboriginal people of the Canary Islands, the king of evil lives inside this volcano.

Lava stone structures possibly dating back to the 19th century may have been a stopping point for voyagers between ancient Egypt and the Mayan Civilization.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

An outsider folly near Madrid.

12th-century holy complex shares land with a natural park full of heavenly waterfalls and raptors.

A completely underwater art museum sends a stark message about humans' impact on the environment.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.