Five mysterious spheres in the wall of a church that puzzle Málaga’s locals.

The enchanting archway is the only surviving portal into Dublin’s lost medieval wall.

This statue celebrating everyday life in Dublin has a few unsavory nicknames.

This store may be part of a well-known chain, but it stands out due to the tree growing through the middle of it.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

Built for herding sheep, these tiny winding lanes with medieval origins and distinctive series of narrow turns are charming walkways for humans today.

This ingenious engineering solution was built to stop the "theft" of canal water.

The largest public library in the United Kingdom was designed to reflect the industrial and artistic history of the city where it stands.

An ancient woodland that inspired a young J.R.R. Tolkien.

A mountaintop shrine named for the road to heaven.

This house's itty bitty size means no humans allowed.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

Vibrant street art created with mixed media.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.

Local legend says Isaac Newton built this footbridge without any screws, bolts, or nails.

The sanctuary seems to either float atop the water or sink into the dirt, depending on the water level.

This Art Nouveau gate still stands at the former entrance of a 20th-century Spanish writer's colony.

The oldest building in Madrid.

A towering monument in Spain has proven to be more labor-intensive than initially planned.

A magnificent, long-abandoned castle built in the wake of the reconquest of Spain.

Once a resting spot for King Fernando VII.

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

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

A beautiful little castle with a rich history now home to the Archives of the Spanish Air Force.