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

Rebuilt remains of a temple to Roman god Mithras.

One part local history, 99 parts gruesome haunted house.

An unusual round church in London with a Templar past.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

The spot in the Mile-High City that's exactly 5,280 feet above sea level (at least for now).

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

New Jersey's last historic covered bridge was rebuilt from pieces of the original 19th-century structure.

Abandoned businesses, homes, and rusted cars are all that remains of this stopover town.

Every president in history is immortalized in bronze in downtown Rapid City.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

This replica stave church looks like a piece of Norway was simply plopped down in South Dakota.

One of America’s oldest and spookiest hotels, thanks to the residency of ghosts, dead presidents, and Alfred Hitchcock.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Other-worldly rock formations and ancient fossils abound in this unique stretch of Nebraska badlands.

Population: 1.

A small Wyoming town is home to the state's oldest-operating soda fountain.

A towering tribute to decisiveness stands on the spot where Brigham Young and his followers decided that this must be the place.

This museum remembers the tough Mormon trek across America through an intriguing array of artifacts.

The fifth-longest natural arch in the world, and the longest outside China.