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

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

A surreal botanical garden with an even more surreal tour guide.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

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.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

An exclusive waiting room built for the royal family in the 1920s is hidden in Milan’s central station.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

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

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

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

100 year tradition of fist fights, marked by marble footsteps.

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

A lover's walk between hilltop towns, decorated with graffiti love notes.

This statue of the great Argentinian car driver is located near a famous curve of the Monaco Grand Prix.

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

This massive blockhead sculpture hides an entire library.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.