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

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

Twisted buildings adorn the banks of the Rhine river.

This futuristic German television spire is actually the world's largest digital clock.

Drink the 'Blood of Christ' in this Roman Catholic fever dream.

In the world's oldest university is a stunning 17th century anatomical theater carved from spruce.

A large statue of Pope Gregory XIII in Bologna was disguised as Saint Petronius to avoid destruction.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

In one of the smallest countries in the world stands an original Salvador Dalí sculpture.

The world's tallest church tower reveals a spectacular view to anyone up to the task of climbing the daunting staircase.

A small but immensely extravagant palace built by the "Night King."

The fairy tale castle of the "fairy-tale king."

A unique bridge with an equally unique view.

A theatre built to house the rowdy Oxford graduation ceremonies became the stage for a debate about God's existence.

The spot where three Protestant clergymen were burned at the stake during the reign of "Bloody Mary."

Famously misunderstood wonder of the ancient world

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.