A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

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

A historic neighborhood church is reborn as a psychedelic arts collective.

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

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

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

The United States Capitol's former columns still stand.

Beyond being incredibly fun, not much can be said about the Hole with certitude.

The atmospheric road was never meant to be so creepy.

Swedish skyscraper with a 90° twist.

Swedish mice can dine at the Nuts of Life restaurant or take a date to the amousement park.

Old Danish castle immortalized in Shakespeare's Hamlet.

Six beautiful wooden giants are hidden around Copenhagen.

Nordic giants resurrected from the sea and restored to their former greatness.

The oldest amusement park in the world has been providing a nice spot to have some fun since the 1500s.

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

Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

This ultra-modern wooden boardwalk turns the ocean into a swimming pool.