A clock designed to run with perfect accuracy for 10,000 years.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

A collection dedicated to the treatment of disease, held in London's oldest hospital.

One part local history, 99 parts gruesome haunted house.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

A historic house left in "dramatic still life."

A mysterious carving from 17th-century London seemingly depicts a young boy sitting on a bread basket.

The library houses an incredible collection of some of the world's most impressive books and manuscripts.

William Smith's iconic "map that changed the world" is hidden behind a curtain in the Geological Society building.

This small collection of rare books was uniquely locked up for safe keeping.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

A rare water-powered funicular, it uses a huge tank of water and gravity to do its work.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

Since 1874, this macabre collection has developed into a museum devoted to Scotland Yard's mementos of dastardly deeds.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

The remains of a paranoid inventor's hidden workshop lie in beautiful ruins amidst a Canadian park.

A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

The stunning remnants of this wreck emerge from an otherworldly backdrop of rainforests.

This mysterious Sardinian festival sees a horde of blank-faced equestrians compete for tin stars.

The "beautiful" equation predicting the movement of all electromagnetic particles is engraved in front of Newton's tomb.

Numberless clock creates a meal of time for the dreaded, insectile Chronophage.

Hundreds of secret cabinets built into the walls of legendary poisoner's private work room.

Legends surround this jagged rock formation in the New Mexico desert.