The remains of Crystal Palace Great Exhibition of 1851.

Hidden beneath the streets of London is a secret subway that only carried mail.

An artistic tribute to the famous singer, just around the corner from where he was born.

Tombstones and enigmatic inscriptions hide within a vault beneath a popular London arts venue.

A historic hill of tall tales, with one rather special tree.

An unassuming London park is actually a pilgrimage site for modern clowns.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

A cluttered and astounding collection of antiquities and curiosities.

Victorian-era Londoners really wanted to believe this 17th-century cistern was actually an ancient artifact.

A tongue-in-cheek arcade where the games are based on everyday life.

Shiny Brutalist box commemorates a pioneer of electricity and houses a railway transformer.

The anatomical-pathological collection of a man who changed surgery.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

An unusual round church in London with a Templar past.

Taxidermied animals galore, by appointment only.

Dictionary Johnson’s favorite feline.

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

An abandoned tank sits in an empty London lot as a symbolic middle finger to local city planners.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

The largest of London's subterranean rivers and once a mad, bad center of London life.

The London statue that imitates passersby.

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