More than a million titles fill the labyrinthine shelves of this prestigious private library.

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

Installed at a chaotic intersection, this gave London traffic cops a place to hang their heavy woolen coats.

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

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

These morbid carvings remind churchgoers of the inevitability of death.

This overlooked street light once served as a KGB dead letter box.

A museum wholly devoted to juvenescence.

This elaborate Byzantine-style building was designed for a not-so-pretty purpose.

Revel in the Victorian splendor of the world's oldest eating establishment inside a museum.

Public access to clean drinking water was an instant hit among the masses.

A famous burial ground with a history both grim and literary.

This artist's home turned gallery/museum preserves the creator's love of "Eastern" influences.

A relic of Victorian grandeur hides beneath a busy South London road.

The cedar tree in Highgate Cemetery earned its title by accident.

Eclectic final resting place of the controversial explorer.

Traveling collection of amazing automata.

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

Pop culture has helped to keep this iconic British building from being destroyed.

A Roman spa buried deep beneath the City of London.

This museum tucked below a charming cafe gives a brief snapshot of photographic history.

This home on a quiet suburban street is completely covered with vibrant mosaics.

The pioneer of psychoanalysis spent the final year of his life here, still seeing patients on that famous couch.

Following the trail of an old metro line, this scenic path is haunted by a creepy spriggan statue.