This historic black and white monastery is one of Bulgaria's architectural jewels.

A little sculpture with a large wardrobe.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A solar-powered primary school inspires hope and experimentation in a country ripe for energy innovation.

Three floors of musical instruments coming from all corners of the world and hundreds of years of musical history.

Climb inside an iron crystal magnified 165 billion times its normal size.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

Avoid gangster interaction while window-shopping.

An artist's cute bronze subway sculptures belie his violent artistic past.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Mysterious 500-year-old tapestries depict a unicorn hunt.

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

Elevated freight railway turned wildly successful urban park.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

Go inside a revolutionary, cage-less zoo where 70 species of monkeys roam free alongside their human visitors.

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

Dancing skeletal figures pay homage to a medieval mural destroyed during World War II.

Executed in 1401, Exhumed in 1878, Stolen in 2010.

A tilted half-timbered house from 1672 is built into a salvaged segment of a medieval wall.

The small alleys in Lübeck's Old Town are a result of medieval urban sprawl.

This contentious squat has stood through fire, violence, and government intervention as a hotbed of leftist protest.