The discovery of an old wall led to the creation of this fascinating museum about the city in the Middle Ages.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

Dine on food tied to Viking history and legend at this subterranean Stockholm spot.

This spooky statue sits outside a famous Prague theater.

Walk through Czech history in Prague's largest graveyard.

This enormous secondhand bookstore inside a Victorian train station sparked the "Keep Calm and Carry On" craze.

A million and a half tons of earth were used to create one of the world's largest land sculptures.

This triumphal 16th-century arched gateway leads to the oldest street in Palermo.

In downtown Oslo, a menacing and terrifying relief clings to a church wall.

A museum celebrating the Canadian forces that liberated Belgium from the Nazis replete with battlefield miniatures and multiple Gardens.

This former Masonic lodge has been transformed into part museum, part bar, all awesome.

Christ's blood preserved in a Belgian town.

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

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

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

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

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

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

The world's oldest bookshop still in operation.

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

The nearly 200-year-old folly has a secret spiral staircase hidden in one of its pillars.

This gorgeous space is England's largest independent library outside of London.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

The medieval woodcut-style artwork chronicles life in medieval London.