One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

At this rare mosque in Tbilisi, Sunni and Shia Muslims pray side by side.

This ancient monastery complex was transformed from an island to a peninsula when the lake was partially drained.

A towering monument to war, located on a beautifully peaceful hill.

Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

A medieval church built up to defend its village.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

A quirky bookstore hidden beneath a sea of whitewashed Greek villas.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.

This once-derelict building is now one of the most beautiful bookstores in the world.

This Ukraine alleyway has become its own little island of forgotten things.

This attraction was abandoned after the Chernobyl disaster.

This derelict superstructure was a very important warning system for the Soviet military.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

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

This rare basilica nestled right in downtown Asheville is an architectural marvel, inside and out.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

A popular European tradition makes its way to the states on one of America's most famous bridges.

Fantastic views and thousands of love locks.

From Nazi chemicals to the CIA, this architectural marvel has played a fascinating role in German history.

One of the world's heaviest musical instruments towers within a popular urban park.

An ultra-modern diversity park in Denmark has turned an entire city block electric pink.

This sublime architectural marvel is a rare example of an expressionist church.