One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

The storefront of a ramshackle Parisian puppet theater.

A short distance from the Eiffel Tower is the final resting place of several of the city’s more well-known and interesting characters.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

The oldest and smallest cemetery in Paris is only open to the public twice a year.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

This museum in a Paris apartment gives a unique look at the iconic French singer's life.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

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.

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

Down a cobblestone alleyway is a museum dedicated to Romanticism, with a secret garden.

A surrealist timepiece by the artist of melting clocks.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

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

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

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

Abandoned railway line circling the city of Paris.