A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A marvel of Byzantine engineering under the streets of Istanbul.

The ornate miniature mansions were built for Istanbul's feathered residents.

A garden in Lisbon filled with giant porcelain creatures.

The best place in the world to buy tinned fish.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

This semi-secret storybook hedge maze is also the oldest garden in the city.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

London's old-school healing garden.

On the outskirts of Edinburgh, a trio of topiary created by one man over the course of more than 20 years.

This cannonball embedded in the side of an Edinburgh house once served a surprisingly pedestrian purpose.

A miniature of a lighthouse acts as a beacon for what transpires inside this location.

A sculpture in a secluded garden honors one of Edinburgh's most innovative thinkers and city planners.

This modern work of art was a refreshing addition to one of the oldest theatres in the city.

This extinct volcano rises above Edinburgh and is special for its panoramic views over the city.

A public art piece that barely gets recognized, but then that might be the point.

This 16th-century close preserves an unusual piece of Edinburgh's transportation history.

Brass bricks outline the locations of Edinburgh's lost, lively market stalls.

Neon artworks light up this dark Edinburgh tunnel.

The 20th-century chapel’s intricate woodwork includes amazing details, most notably angels playing bagpipes.

This former train tunnel is filled with lines from a poem crafted by Robert Louis Stevenson.