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

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

Abstract dinosaur models in London.

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

The television series' iconic giant foot was borrowed from this classical painting.

A network of concealed passageways lies within a busy London Underground station.

A cluttered and astounding collection of antiquities and curiosities.

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

Hear the quietest sound from across the dome.

An incarceration museum on the spot of possibly the oldest prison in England.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

This 1920s Dutch barge is now a floating bookstore.

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

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

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

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

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

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

Gigantic private toy museum featuring among finest collections of antique mechanical banks in existence.