One of Madrid's oldest trees, with a long and colorful history, resides in El Retiro Park.

An iconic and controversial ancient Iberian funerary urn with a hauntingly penetrating gaze.

Commonly acknowledged as the only public monument to the Devil himself.

A lush indoor jungle fills this bustling Madrid transportation hub.

This chimerical bridge/tunnel appears to dead end right into the sea.

Swedish skyscraper with a 90° twist.

This small museum nestled inside a souvenir shop is dedicated to Sweden's most well-known toy.

Stockholm's narrowest alley is barely over two feet wide.

The discovery of an old wall led to the creation of this fascinating museum about the city in the Middle Ages.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Sweden's "good old days" painstakingly re-created in a model village.

The library's graceful rotunda is like a bibliophile's temple.

It houses the remains of a 17th-century version of the Titanic.

Giant topiary dog once played a role in a terrorist bomb plot.

Ancient paintings known as the "Sistine Chapel of Cave Art."

Designed as a reminder of one of the darkest moments in Austrian history.

In the middle of a Vienna square, Roman ruins dating back some 2,000 years are on display.

Op-art architecture designed for happiness.

Handsomely crafted representations of our round planet.

Dine amidst exotic plants at this former royal greenhouse.

The topiary maze at the Habsburg hunting lodge.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

The beautiful baroque library of the Hapsburg empire.

Baroque celebration of the end of the Great Plague of Vienna.