The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

A statue honors the children who fought Nazis in Poland.

An artificial date palm stands as a memorial to Warsaw's Jewish community.

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 German apartment building hosting as many trees as human occupants.

American soldiers discovered Europe's best one-liner at the end of World War II.

"Medieval" castle built in the mid-20th century by one family.

One of the largest barracks of the Austro-Hungarian monarchy's military is now an abandoned ruin.

In this brilliant blue spring in Germany, legend has it that a sad mermaid learned to finally laugh.

One of the most easily accessible examples of the rare 1960s UFO houses.

Go surfing on this urban wave, "hacked" by local surfers.

This beautiful 19th-century temple stands atop the ruins of its predecessor.

These blingy, baubled skeletons lie in glass boxes inside a baroque Bavarian church.

Albert Einstein's head sticks out of a snail shell stacked on a rocket in this truly bizarre monument to the scientist.

This historic Art Nouveau townhouse was the former home of the son of a famous chemical inventor and industrialist.

A former smuggler's haven houses "The Chapel" and its mysterious carvings.

This seaside property, an example of Art Deco Streamline Moderne style, was designed to embody the curves of a great ship.

Decrepit Victorian public lift is a white-knuckle ride.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

This well-preserved Cistercian Abbey in a romantic pastoral setting has inspired artists like the poet Wordsworth.

A 16th-century horror show built in a lovely Italian garden.

A self-built mosaic house and sculpture park.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.