The randomness of this wall of lava lamps helps encrypt up to 10 percent of the internet.

Public outcry led to this bridge's unique character which celebrates a giant frog battle and also sewing.

The legend of a local monster still haunts this small town.

For over 100 years, this Indiana town has had a tree growing out the top of the local courthouse.

The tiny, studious rodents greet visitors to the National Archives of Finland.

The menacing creature had a tremendous influence on the local culture before being exposed as a hoax.

A hidden three-foot-wide house separates these two regal churches.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

When it comes to handsignals (and colonialism) rock always beats scissors.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

The most accurate timepiece in the world.

Housing the National Women's Party since 1929, this historic house is now a monument to the fight for gender equality.

A computer bug so primitive it was an actual insect.

The most decorated dog of World War I is preserved in the Smithsonian.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

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

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

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

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

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

Home to items never before seen by the public.

Monty Python fans will recognize this abandoned mine as the Cave of the Killer Rabbit of Caerbannog.