The world's largest wooden structure.

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

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

Bacteria and algae give the salty water its bubblegum hue.

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

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

This museum is a portal to 20th-century Denmark.

A typographic tribute to the many comedic greats who make Great Britain laugh.

A lonely beacon, precariously perched atop a remote sliver of rock.

This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

Centuries of human activity have forged an eerie landscape of ruins and craters on an exposed and windswept hilltop.

The largest of only eight working transporter bridges left in the world.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

The first skyscraper to include a Ferris wheel built into the facade.

This beautiful example of Victorian engineering is the oldest water-balanced funicular anywhere in the world.

The widest waterfall in Europe is a natural wonder and one of the only places where fish are caught in the air.

An abandoned giant glass dome sits in the bay in “the Venice of the East.”

This strategic isle was once swapped between empires and almost entirely destroyed in a bomb explosion.

Hidden beneath the streets of London is a secret subway that only carried mail.

An elevator into the Baltic Sea.

The place to be if you love vintage Swedish cars.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

Two volcanic lakes in an enormous crater formed in a prehistoric eruption.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.