Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

An archeological treasure trove stumbled upon by a couple of children.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Its collection details the experiences of the largest Japanese community outside Japan.

A former prison complex now displays a historic collection of inmate artwork.

The bookstore with bookshelves built into unlikely places.

The eccentric home of Estevão Silva da Conceição, known as the "Brazilian Gaudí."

The crypts are so large they're basically their own underground church.

A museum dedicated to the Spanish occult in a town that was terrorized by the Inquisition.

Semi-mystical manmade towers of rocks decorate this rocky seaside.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

A stately palace has been converted into the world's largest cannabis museum.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

A temple to modernity, tucked away amid Barcelona's more well known museums.

18th century anatomical amphitheater of the Royal College of Surgery of Barcelona.

Mysterious Spanish catacombs of unknown origins.

A huge cathedral single-handedly constructed by one eccentric monk.

This funky former tobacco factory is one of the most striking examples of Madrid's cultural diversity.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

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

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

One of the world's oldest universities houses an incredible collection of anatomical models, mummified body parts, and human bones.

The earliest known map to show America, discovered by accident at a Paris bookshop.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.