This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

A Jenga-style cylindrical tower of books that appears to go on forever.

Macabre astrological automaton clock dating to the late 1400s.

A little sculpture with a large wardrobe.

This historic streetcar system has been running since the 19th-century.

This giant sculpture made of trash is a critique of society's wastefulness.

Elaborate tile work in this railway station tells the story of Portugal.

A hidden three-foot-wide house separates these two regal churches.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

Over the course of its history, this tiny island has held enslaved people in transit and served as a quarantine zone. Today, it's a giant tortoise sanctuary.

This monument is a stark reminder of the horrors of the Zanzibar slave trade.

In Zanzibar, a historic 19th-century palace is a reminder of the world's shortest war.

Freddie Mercury's childhood home is now a monument to the iconic Queen rockstar.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Breathtaking and huge 430 year old maps of Italy.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

Drink wine handed out through a window as part of an age-old tradition.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

This modest marker near Notre Dame identifies the very center of Paris.

Trek up this glacier before it disappears.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

Barcelona's only remaining tram system takes riders to the Tibidabo funicular.