A rotating cast of guys and dolls in front of a Washington, D.C. building.

There’s a hidden military meme engraved on the World War II Memorial.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

The site of the climactic scene from the classic horror film is now a historic landmark.

Home to items never before seen by the public.

This Stockholm art museum integrates many of its pieces into the surrounding outdoor areas and natural landscape.

Sweden's southernmost prehistoric rock art is hidden just outside Gothenburg.

A golden egg-shaped sauna in the Arctic tundra.

The dome-shaped reservoir of this old water tower produces unique acoustic effects.

This cobblestoned medieval-style town was entirely constructed in the 1990s and 2000s.

An 11th-century runestone decorates the halls of Terminal 2 of this Scandinavian travel hub.

A former suicide bridge is now accumulating symbols of love instead of a body count.

This chimerical bridge/tunnel appears to dead end right into the sea.

Micro-nation based around a nine-story high illegally built tower.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

The world's first ice hotel is still one of the most elaborate and beautiful.

Sweden's "good old days" painstakingly re-created in a model village.