The partially submerged ruins of a white marble quarry used in ancient Greece for over 1,200 years.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

This massive library holds what was once the largest book collection in the world.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

A magical, macabre wax museum, beloved by locals, uses real artifacts to depict an assassination from the French Revolution.

France's most famous cemetery, with some of its most curious tombs.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

The oldest stone house in Paris was built by its most famous alchemist.

France's national museum of scientific and industrial instruments.

An off-the-beaten-path boutique stuffed with an eclectic collection of upcycled goods.

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

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

A Roman spa buried deep beneath the City of London.

Rebuilt remains of a temple to Roman god Mithras.

This legendary stone is of unknown origin, and throughout history has been a literal touchstone for British leaders.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

A movable feast that is an East London institution.

East London art gallery showcasing contemporary art from Europe's Eastern Bloc.

A boutique perfumery fashioned to look like a Victorian-era shop.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

English antique dealers with a taste for the unusual.