The commemorative stone column conceals a secret laboratory.

A Roman spa buried deep beneath the City of London.

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

The Columbia Road Flower Market is now open every Sunday, rain or shine.

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

Rebuilt remains of a temple to Roman god Mithras.

One part local history, 99 parts gruesome haunted house.

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

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

Open for a weekend once a year around October it houses a fascinating collection of unique Victorian preserved and stuffed animals.

Museum about life, death, and cannibalism in the Stone Age.

Catacombs turned marketplace.

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

The world's largest collection of witchcraft regalia.

The sign at the garden gate reads: "These Plants Can Kill."

These fantastically named natural pools look like something out of a Scottish myth.

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

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

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

This museum houses an imposing skeleton army comprised of creatures great and small.

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

The vast, legendary catacombs hold secrets much stranger than stacked bones.