Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This fortress dates back to the 6th century and is also the site of a controversial abandoned restoration project.

This mosaic-lined medieval church was built by the world's first admiral and still holds mass in ancient Greek.

Behind medieval walls in a corner of bustling Palermo is a breathtaking former mosque once inhabited by a wolf-taming hermit.

These light, hollow rolls have been linked to Acadia National Park since the 1890s.

The celebrated eyesore created by starry-eyed sweethearts.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

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

The design of this beautifully crafted building was inspired by Norwegian glaciers.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

This hidden oasis features a stunning view of the Hudson River and the Palisades from a castle-like museum.

Mysterious 500-year-old tapestries depict a unicorn hunt.

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

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

Historic medieval fortified city in southwest France.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

The most visited, and possibly most controversial, museum in Germany.