The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

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

2300-year-old Roman road connecting the empire.

The yawning maw of this pagan visage is said to bite off the hands of liars.

A stunning gilt bronze relief denounced by Hitler as "degenerate art"—even though it was dedicated to the Nazi leader.

A spitting ode to a German serial killer.

Böttcherstraße's bells, extolling Nordic virtues and the great conquerors of the world.

Eight naturally mummified bodies in glass coffins are housed in an underground crypt.

Model Trains and Much More in Hamburg.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

The Brutalist building harbors an unusual inverted dome that swoops down over its central sacred room.

This floating sculpture of ice is a poignant reminder of nature's power.

This striking royal residence is the largest Renaissance-style castle in Scandinavia.

A stunning two-story timepiece within a medieval Brick Gothic church.

A statue honors the local legend that the devil helped build St. Mary's church after being tricked into thinking it was going to be a wine bar.

Visitors are treated to a stained glass kaleidoscope interior inside this work of art.

The world's first combination ski slope and power plant.

Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

20-foot tall lamp mumbles Swedish to celebrate the holidays.

These unique stained glass windows were designed by local children using a modern flair.