An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

This elaborate tunnel is the first structure composed of cast concrete in the United States.

A tree that grows parallel to the ground was declared Brooklyn's "crowning curio" by the poet who saved it.

Wine bottle sculpture with a ship's stateroom inside.

Banksy's image of a naked man dangling from the window of a sex health clinic.

The abandoned funicular tunnel was a secret base for the BBC during World War II.

After protestors toppled a statue of a 17th-century slave trader, the pedestal where it once stood remains unoccupied.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Go inside to really appreciate this 500-year-old technological masterpiece.

Where Venice's gondolas go for a tune-up.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Despite their macabre past, these hooks are said to bring good luck to those who touch them.

According to tradition this is the oldest church in Venice, but its actual age is a mystery.

You can cross from one country to another in a single hop on this little bridge.

The atmospheric ruins of a historic church can be found on a hill above the city of Oviedo.

The much-loved protagonist of famed Argentinian comics can be found sitting on a park bench.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

This 19th-century fountain's namesake animal isn't what you think it is.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

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

The ruins of a 16th-century bridge loom over Olivença's sovereignty.

A comprehensive look at the art of Joaquín Sorolla in his former home in Madrid.

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