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

The narrowest street in Paris.

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

A surrealist timepiece by the artist of melting clocks.

The video game-themed street art first popped up in the French city.

The remains of the medieval wall that once surrounded Paris with ties to the construction of the Louvre.

An unusual number plate signifies the building's saucy past.

A poem by Arthur Rimbaud is inscribed on the wall of a street that, while it is only one block long, plays a key role in multiple novels.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

The Tudor-style cottage in the middle of the square is not quite what it seems.

This museum tucked below a charming cafe gives a brief snapshot of photographic history.

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

Black cat statues guard this temple-like Egyptian revival factory.

Catacombs turned marketplace.

A totem pole of heads to represent the different stages of life.

A friendly pub with a sordid past in cock fighting.

The bridge is a secret gallery of discarded gum that has been transformed into miniature masterpieces.

This building contains a door only used by members of the royal family.

The ruins of a church destroyed by both the Great Fire of London and the Blitz, now turned into a peaceful garden.

A mysterious carving from 17th-century London seemingly depicts a young boy sitting on a bread basket.

What might be the oldest living tree in London has survived fires, bombings, and estate agents.

Near the site where the English Archbishop was born, you can find an emblem in the shape of a pilgrim's badge.

Rebuilt remains of a temple to Roman god Mithras.