This hidden green space is the city's second largest conservatory.

Repository for more than 22 million pickled specimens.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

The remains of Crystal Palace Great Exhibition of 1851.

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

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

Legend has it fairies gathered at the site of this medieval castle.

Hidden beneath the waters of Lake Michigan rests a perfectly intact ship from the early 1900s.

Incredible miniature towns and buildings created and decorated with thousands of tiny rocks.

Just a few miles from downtown Atlanta is a trail covered in a crazy collection of outsider art.