This religious museum resides in a church crypt next to the founder's house.

An ornate and disused early 20th-century building has been given new life as a fully operational structure, complete with offices, oyster bar, and a furniture retailer.

The final resting place to 300 Victorian-era pets hides inside the city park.

One of the world's largest collections of pathological specimens.

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

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

Rebuilt remains of a temple to Roman god Mithras.

A secluded green oasis amidst the towering skyscrapers, bears an unusual moniker that reflects one of the city's oldest guilds.

This South London cemetery holds the remains of more than 15,000 people.

A tiny replica of the iconic London landmark hides on the side of the steel structure.

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

Hear the quietest sound from across the dome.

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

One of the oldest remaining Catholic churches in England is home to the hand of a 7th-century saint.

The London statue that imitates passersby.

A collection of machines designed to break things for science.

It is still illegal to "quarrel" at this unlikely urban oasis built on top of an electrical substation.

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

Tucked away behind the mansions of Mayfair, this picturesque garden is a hidden London treasure with a spooky past.

Buried for centuries, this hidden cellar is all that remains of London's medieval Whitefriars Monastery.

The secret wartime bunker built on the platforms of an abandoned Tube station.