A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

One part local history, 99 parts gruesome haunted house.

After a short-lived attempt to bring America in line with the rest of the world, this road was left in metric.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

A sewing machine tycoon built this miniature castle for the people and to beautify a lakeshore.

One of the longest water bridges in the world was built over a supposedly haunted swamp in Louisiana.

This Memphis recording studio launched the careers of Jerry Lee Lewis, Johnny Cash, and Elvis Presley.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

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

Washington's iconic carousel has a nice piece of Civil Rights history.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

Decades before the scandal, this staircase on the river was a literal "water gate."

The most accurate timepiece in the world.

Where the U.S. government kept its actual treasure, before Fort Knox.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

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

The "lovely red Vega" of the legendary record-settling pilot.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

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

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