Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Remarkably intact Roman stone fortifications have encircled this Spanish city for centuries.

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

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

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

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

A Gothic cathedral created from volcanic rocks.

A chapel on a volcanic core, marking the end of a successful journey.

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

Giant topiary dog once played a role in a terrorist bomb plot.

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

The world's tallest bridge is also possibly the most elegant.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

The world's most famous cheese caves.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

Historic medieval fortified city in southwest France.

Immortalized by artists, this church incorporates a medieval lighthouse into its shoreside structure.

A breathtaking canyon offers stunning views and frightful pathways through an ecological paradise.

Stunning Roman aqueduct used for 1900 years and still standing.

A Romanesque tower appears when water levels drop.

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.

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.