The mental institution where Van Gogh created some of his most famous work now allows guests to walk in the artist's footsteps.

The bronzed skull of a beheaded traitor was affixed to the city gate in the 17th century.

A trio of red, white, and blue stones embedded in the streets of Leiden are markers of medieval territory and law.

A massive explosion that leveled hundreds of buildings in the city of Leiden is remembered by a waterside plaque.

Science meets wall art to highlight the beauty of famous mathematical equations.

The remains of a medieval wall discovered in the basement of a jewelry store.

The works of poetry's biggest names grace the walls of the city of Leiden, all carefully painted by hand.

Historic medieval fortified city in southwest France.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

This ancient theater was once the home of fierce gladiatorial battles.

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

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

This historic Amsterdam bar used to accept sailor's monkeys as payment.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

Amsterdam's former hotspot for public executions and dissections.

This gruesome biblical parade celebrates the one day a year that a bit of Jesus' blood turns to liquid.

Christ's blood allegedly preserved in a Belgian town.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

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

Commonly acknowledged as the only public monument to the Devil himself.

This whimsical winery by Antoni Gaudí looks ripped from the pages of a fairytale.

This unattributed sculpture in Amsterdam is hiding in plain sight.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.