Valletta’s outdoor theatre stands within the ruins of a 19th-century opera house.

This church is named for one of the most dramatic tales in the early Christian church.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

Rumors and legends of secret Nazi activities surround this eerily remote island mansion.

Stone dwellings of the Mahos, Fuerteventura's original inhabitants

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

This museum housed in a former brothel explores the past and present of sex work in Amsterdam.

A beautifully eclectic mix of architectural styles.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

Museum preserving torture methods from the past.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

A museum in England’s Lake District dedicated to the trusty pencil wants you to know the story of their World War II spy pencils.

Charles Babbage's proto-computer, painstakingly brought to life.

One of the oldest and certainly best preserved Cistercian abbeys still in existence.

This iconic 1,000-year-old medieval castle is a favorite of the film industry, most notably as the location for Hogwarts in Harry Potter.

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

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

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

The yawning maw of this pagan visage is said to bite off the hands of liars.

One of the best-preserved medieval streets in Europe.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.