A subterranean house of worship carved right out of the bedrock.

Modern art commemorates one of the first military actions of World War II.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

A small marionette collection located within the dark cellars of an 11th-century Austrian castle.

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

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

The place where World War I began.

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

This stunning concert hall has become a symbol of Iceland's national recovery.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

Monuments don't get much more metal than these three giant viking swords planted in a Nordic hill.

This "preacher's pulpit" once used for pagan ritual, is home to a new, and dangerous ritual.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

Beneath the city of Lourdes, France is a massive, concrete church.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Breathtaking and huge 430 year old maps of Italy.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.