The last moments of the ill-fated Pompeiians, frozen forever in plaster.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

In a city that boasts four separate inclined cable railways, this is one of the busiest funicular lines in the world.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

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

Single runway interrupted by a busy road that cuts across its middle.

Giant topiary dog once played a role in a terrorist bomb plot.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This massive library holds what was once the largest book collection in the world.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

These slanted cubic abodes are a creative if odd solution to a zoning pickle.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

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.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.