Two New York rooftops are home to the largest rooftop soil farms in the world.

One of the oldest Jewish cemeteries in the city, it is now overgrown with an urban forest.

Piano-making empire filled with 200-year-old steam machines still churning out 1,000 instruments a year.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

The crown jewel of the Queens Museum is a nearly 10,000-square-foot architectural model of the city originally built for the 1964 World's Fair.

This enormous Hindu temple in Queens serves incredible dosas in its basement canteen.

A kaleidoscopic warehouse-maze of handmade neon signs.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

Moorish signal station on a stratgic rocky outcrop.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Houses are tucked between, on, and underneath giant boulders.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

Vibrant street art created with mixed media.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

The world's largest wooden structure.

Earth's rocky history has rarely glittered so brightly as it does in this Spanish museum.

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.