This aluminum “stairway to heaven” has impaled at least a couple of birds.

The industrial architecture honors the laborers who brought the Exposition Universelle of 1900 to life.

One of the best collections of wax anatomical models in the world.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

This permanent exhibition of commercial signs aims to preserve the cultural heritage of the city.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.

Vibrant street art created with mixed media.

With a facade that measures just 107 centimeters, this five-story building is one of the skinniest in Europe.

The little church's beautifully frescoed ceiling has earned it the nickname “the Sistine Chapel of Madrid.”

A thorough look at the development and history of the underground's rolling stock of the Madrid subway system.

Dedicated to a young woman who broke gender barriers at the University of Madrid.

This unassuming bookstore in the heart of Madrid is one of the oldest in Spain.

Order cookies baked by cloistered nuns in a 400-year-old monastery.

This postmodern apartment block was designed to be a vertical neighborhood.

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.

A lush indoor jungle fills this bustling Madrid transportation hub.

Shop selling 500 flavors of soda has something for everyone.

This decommissioned nuclear power plant offers tours of its Communist-era control room and reactor hall.

One of the world’s longest pedestrian suspension bridges.

This amended headstone marks the grave of a participant in one of the most successful military deceptions of all time.

A relic of the Cold War tucked away in the forested hills above Bratislava.

This enormous steel tube is the biggest speaking horn in the world.

In 1975, a forestry worker in Arizona claimed to have been abducted by a UFO.