An ornate private entrance to the Vienna subway built specifically for the emperor.

Ruins of two abandoned stations destroyed by the power they sought to harness.

A marble Lucifer hides behind the pulpit of this Gothic cathedral.

An early 20th-century sanatorium, long abandoned and now being reclaimed by nature.

Created as a "model concentration camp" to hide Nazi atrocities from the international community, this former camp-ghetto now holds a museum and memorial honoring the lives lost within.

This local emblem is the oldest and largest dragon tree in the Canary Islands.

An unexpected ghost village lurks on the southeast coast of Tenerife.

This Netherlands museum holds a gloriously mechanical collection of ornate musical automata.

This vast World War II defense line was the site of a fierce battle.

This wild explosion of color on a disused water tower tells the whimsical tale of a curious puffin.

The world's largest bicycle shelter can hold more than 12,500 two-wheelers.

This abandoned Greek island was the last active leper colony in Europe.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

A marvel of Byzantine engineering under the streets of Istanbul.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

The history of sea-faring refuse and disaster is on cramped display in this Netherlands folk museum.

A black cat protests the City Guild in Riga's Old Town.

3,000 market stands in five former Zeppelin hangars.

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

This spooky statue sits outside a famous Prague theater.

A mocking tribute to the past and modern leadership of Prague.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

This Prague museum collects brutalist relics and memories from the country's former Soviet rule.