The land is home to swimming ponies and a legendary 18th-century treasure.

A museum dedicated to exhibiting remarkable outsider art.

Berkeley Springs State Park boasts the nation's only monument commemorating presidential bathing.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

Headquarters of the legendary clairvoyant's readings, spiritual hospital, and massage school.

At 207 feet, one of the world's longest continuous escalators.

The national park was once a plantation estate.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

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

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

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

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

Home to items never before seen by the public.

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

Every equinox this Maya pyramid puts on a spooky ancient light show.

Ancient human remains unearthed around the iconic monument.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

A giant white horse drawn on an English hillside may not have been intended to be a horse at all.

Europe's largest prehistoric mound – burial site of a legendary king?

The granddaddy of English geoglyphs dates back to the late Bronze Age.

The largest stone circle in the world has ended up bringing up more questions than it has answered.

This legendary stone is of unknown origin, and throughout history has been a literal touchstone for British leaders.

Scattered throughout London are ancient remnants of the city's former bounding wall.