An underground world of gorgeous, palatial metro stations designed as a nuclear shelter complex.

Giant cauldrons overflow with Uzbekistan's favorite rice dish at this cavernous dining hall.

This castle has links to Portugal’s founding and struggles for independence.

In Spain, the ruins of a Roman military camp sit along a flooded section of a river.

This chapel is the site of a yearly pilgrimage that originated during the Middle Ages.

These narrow stone granaries have been used to store and dry out grain for hundreds of years.

A cluster of granite granaries perched on stilts.

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

Visitors dip into a variety of pools of what was once ice.

The world's most important buildings shrunk to a tiny size.

This spire on an Austrian mountain is wrapped around a long spiral slide and has the world's tallest wooden observation deck.

Apartment complexes built into huge repurposed natural gas tanks.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.

The inverted pyramid design of this station stands out amid Bratislava's urban landscape.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

The majority of the highest mountain in Poland is actually located in a different country.

A serene memorial that honors the adventurous spirits of climbers who lost their lives in the High Tatras.

340-foot statue built to honour the Heroes of the Soviet Union.

This stunning mountain lake was named for a pair of tragic lovers whose statues stand at the center.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

This memorial to a murdered empress took 20 years to design, then spent 30 years hidden away in storage.

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

This tomb of a Sufi mystic is a remnant of Ottoman rule in Hungary.