Site of the first radio and telephone broadcasting companies in Copenhagen.

This quiet bird sanctuary on the Danish coast is home to something not usually found in a conservation area: hunters' cabins.

This unique architectural wonder is home to luxury apartments.

Remnants of the Nazis' occupation of Denmark linger along the sand.

Iron Age "bog person" preserved for over 2,300 years.

A perfectly circular stronghold constructed in the 10th century is now a nucleus of Viking culture housing a museum, village, and reenactment of an epic Viking battle.

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

Once a resting spot for King Fernando VII.

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

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

This risqué sculpture, based on a Hans Christian Andersen fairy tale, caused outrage 35 years after it was erected.

The final resting place of the author who gave us the Little Mermaid, the Ugly Duckling, and many more beloved fairy tales.

This pair of gilded girls atop an Art Deco building in Copenhagen were built to function as a weather indicator.

Museum on earth sciences featuring a recreation of a famous curiosity cabinet.

The gilded, masterful astronomical clock will calculate time, dates, and planetary positions for thousands of years to come.

A little-known cafe in an old copper bridge tower with 360-degree views of the harbor.

This ordinary street was made infamous by a legendary visit from the devil.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Visitors are treated to a stained glass kaleidoscope interior inside this work of art.

A lush indoor jungle fills this bustling Madrid transportation hub.

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

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

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

The last Viking king of Denmark is buried inside the crypt of this cathedral.