Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

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

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

A million and a half tons of earth were used to create one of the world's largest land sculptures.

Huge winged monument in the United Kingdom.

This century-old grotesque has a mysterious history and may not actually be a rabbit.

One of the longest wooden benches in the world snakes around Geneva's Treille Promenade.

A former steam-powered mill from the 1800s is now an industrial park with a giant steel dragon slide.

The final resting place of the great navigator, or maybe his brother.

A 16th-century Andalusian palace.

The world's largest wooden structure.

A glacial pothole was once a hideout for a notorious Scottish outlaw.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

An Irish Memorial commemorating those who perished due to potato blight.

For centuries young Thai men used this Giant Swing as a slingshot to heaven.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

Scotland's oldest medieval bridge is also among the last reminders of early medieval Aberdeen.

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

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.