Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

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

This large garden vase urn has nothing to do with the seventh U.S. President—it was designed by one landscape designer to honor another landscape designer's contributions to the National Mall.

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

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

These upturned herring boats make nifty storage sheds for fishing goods.

This tidal island, a sacred site in early English Christianity, was the target of a notable Viking invasion.

The main gates have been locked since 1745 and will remain so until the Stuart Dynasty returns to the throne.

This unusual 15th-century house of worship once catered to those who sought its healing properties.

Small sculpted heads of prominent phrenologists mark the outside of their former headquarters.

This enchanting hill is home to fairy lore and a sinister local mystery.

Niagara Falls holds a special place in Nikola Tesla's history, so they put a statue on it.

This Niagara Falls tourist trap is a world bright with neon and curiosities that will inspire love, hate, or a mixture of both.

Every St. Andrews student knows to avoid this inscription for fear of a martyr's curse.

A remarkable feat of Victorian engineering across the Firth of Forth.

A remnant of the Roman army's presence on the coast of Scotland.

Reportedly the "most handsome" market cross in Scotland.

The ruins of a 15th-century church once home to priests who prayed for a single family's salvation.

These ruins of a medieval church are full of architectural mysteries.

The ruins of the second of three churches dedicated to the saint in a touristic Scottish town.

Sprawled across the Great Hall ceiling are various constellations and images relating to the zodiac.

This sculpture of disembodied body parts forms a poignant memory of the horrors of World War II.

Now home to a drinking establishment, this building has a macabre history.