These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

Originally envisioned by King Ludwig II to rival Versailles, Herrenchiemsee's "New Palace" remains half-gilded for lack of funds.

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

Since 1768, the pillar at Guildhall Market in Bath has been a hub of economic transactions.

The accidental discovery of this gilt bronze head led archaeologists to find the Roman Baths in the city of Bath

This single room has survived the centuries with almost no deterioration.

An ancient Egyptian temple in the middle of Madrid, Spain.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

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.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

A curious memento mori hangs in the magnificent Cathedral of Segovia.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

The building hides in plain sight in Ribadavia's historic Jewish quarter.

This enormous censer uses a pulley system installed over 400 years ago.

Known as one of the most climbed mountains in the world, this barren peak is permanently bald thanks to an anti-wolf fire.

This park contains a number of standing stones meant to heal and inspire.

Explore nearly 200 years of guitar-making history

One of the world's oldest continually operating bookstores.