This roundabout commemorates the fourth International Polar Year.

An homage to the first Spanish cyclist to win the Tour de France.

This cuddly-looking statue symbolizes the bond between Spain and China.

Once used to calculate the various levels around the country.

This little sun pays homage to a massive gate that once stood at this location.

The world's largest sundial can cast a shadow more than 1,600 feet long.

A statue of a boy looks up at where the famous rival to the Leaning Tower of Pisa once stood.

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

The largest statue of this convex, homogeneous object with just one stable and one unstable equilibrium point.

This easily overlooked memorial immortalizes the scars from the 1956 Hungarian Revolution.

This dragon narrowly escaped demolition.

This girder was hit by a bomb during the Spanish Civil War, but nobody knew about it until 2016.

A neighborhood represented by an apparent geocentric and flat-earth model of the Solar System is hidden in the subway of Madrid.

Automatons that were once removed after one fell from the building.

The magic of Spanish aviation housed under one roof.

This piece of early engineering is rather unknown despite its location in the heart of Madrid.

A masterpiece of Rationalist architecture in the center of Madrid with lizards on it.

One of the oldest masonic temples in the Netherlands, built in 1757.

If you dare visit this fort, fire-breathing hyenas might devour your camels.

Shrapnel, dynamite, bullets and Franco couldn't destroy this bust, rescued and kept hidden as a family secret for over 40 years.

This 18th-century water provider for Aranjuez was refurbished in 2013 only to be neglected again.

Mysterious Spanish catacombs of unknown origins.

Constructed in 1859 as a general store and post office, the store is still used to this day and was featured in the Walking Dead series.

Visible from both land and sea.