Elevated freight railway turned wildly successful urban park.

Try not to get slimed in Tribeca.

A crumbling hospital from the 1850s on Roosevelt Island.

A terrific purveyor of natural history objects and curios.

The very first subway station in New York City is beautiful, decked out in chandeliers, and ... abandoned?

Edinburgh's oldest statue hides within a parking lot behind the city's iconic cathedral.

A six-ton wedding present for the King of the Scots.

The world’s first museum dedicated to the history of childhood opened in Edinburgh in 1955.

This alley off Edinburgh's Royal Mile contains remnants of the city's seedier history.

The final resting place of soldiers' loyal canine companions.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

The taxidermy remains of the first mammal ever cloned from an adult cell are on display in Edinburgh.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

360° views of the city plus five floors of optical illusions and hands-on science.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

You have to know where to look in this rather ordinary-looking square to find hints of its past as a dissidents' cemetery.

With its vast selection of books, comics, and records, this nearly 70-year-old open-air market always rewards the patient browser.

These small sculptures pay homage to the lovable star of an iconic Argentine comic strip.

A vast necropolis where you'll find the elaborate mausoleums of Argentinian tango stars.

This beautiful fountain was sculpted by a female artist who was ahead of her time.

105-foot wide giant metallic flower blooms anew every day in the heart of Buenos Aires.

A tower devoted to — and modeled after — the Divine Comedy.

A bright little alley in La Boca is a part of tango history.