The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

A road runs through the middle of this small Austrian chapel.

The oldest stone house in Paris was built by its most famous alchemist.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

100 massive sculptures in the Hudson River Valley.

A creepy statue of a hooded ghost hauls itself up from the water in a historic Lithuanian city.

This "living building" on Georgia Tech's campus is home to a blueberry orchard, honeybees, and more than 900 solar panels.

The building features one of the last remaining free-floating spiral grand staircases in the U.S.

This floating garden in the sky is straight out of a fairy tale, but the real thing is nothing short of magical.

One of Chicago's last seafood smokehouses perfects a dying breed of fishcraft.

An old limestone mine transformed into a beautiful and unusual sculpture museum.

This unusual elevator doesn’t stop or slow down.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

A subterranean world of tunnels links several buildings of this rare 19th-century asylum.

An ancient octagonal weather station named for the eight Greek gods of wind.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

A centuries-old forgotten underworld lies beneath Malta.

One man spent 10 years building a spectacular section of road because no one else would.

An abandoned lighthouse awaits its destiny: being buried under shifting sand.

Four alabaster giants contemplate the tides on the shore of Denmark.

A model memorial to the original Odin Tower, the second highest tower in Europe before it was sabotaged by Danish Nazis.

A small Denmark town displays a pair of titanic jaw bones as their community symbol.

In legend, this ancient dolmen was said to have been created when a troll tried to destroy a church.