Come to this Polish museum to take a good, clean look at filth.

This picturesque castle in Poland has a rich history, including a legend that ties it to lost Incan treasures.

A delightful museum entirely dedicated to the tiny homes of dolls.

A merchant court dedicated to the fictitious King Arthur is heavily adorned with bizarre Renaissance art.

This 13th century Gothic brick castle is the largest in the world by surface area.

One of the world's largest collections of medieval religious art.

The final resting place of more than 200,000 people, this is one of the largest cemeteries in Europe.

A peculiar family mausoleum built by a German nobleman captivated by the occult.

An abandoned Nazi explosives plant founded by the inventor of dynamite is now an underground museum.

Warsaw's fantastically preserved gasworks...almost.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

An underground city of salt.

Countless stories attempt to explain Poland's mysterious J-shaped trees.

The site of the first battle of World War II.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

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

The luxurious circular mansion built for a Communist leader now lies abandoned.

The observation point offers spectacular views of the ruins of an ancient Armenian capital.

This little medieval church hidden in the center of Yerevan was lost and rediscovered—twice.

Nestled in a peaceful valley, this Armenian monastery may have been saved from Mongols thanks to the eyes of God.

The ruins of a medieval monastery built on a perilous slope.

This medieval manuscript collection has some of the most obscure and ancient texts in the world.