Scattered throughout London are ancient remnants of the city's former bounding wall.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

The remains of Crystal Palace Great Exhibition of 1851.

London's smallest police station is barely the size of a phone booth.

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

Hear the quietest sound from across the dome.

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

A little slice of Japan and its aesthetics in London's Holland Park.

Rebuilt remains of a temple to Roman god Mithras.

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

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

Eighty million natural history specimens call this gargantuan museum home.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

Used as an example in one of the first dictionary entries for "museum" in 1706.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the 20th century.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The longest continuous underwater road in North America was built at the insistence of Franklin Roosevelt.

This unusual subway stop was originally a real estate office.

This beautiful Brooklyn monument over a crypt memorializes a grim and largely unknown story from the American Revolution.

Spike Lee's provocative film is officially honored right where it was made, the first time a work of art was used as a secondary street name.