If you visit the burial place of King Frederick the Great, you'll likely find a couple of potatoes sitting on his tombstone.

Solar observatory doubles as a daring display of Expressionist architecture, much to Einstein's chagrin.

The "Prussian Versailles" that is as glorious today as when it was built.

The first, and perhaps only, monument dedicated to Wikipedia.

An abstract and eyecatching clock/fountain is the centerpiece of this little-known German city.

A slice of central Asia in the middle of Berlin.

This unique medieval artwork featuring the story of the Antichrist remained lost for decades.

In addition to showing films, this one-screen arthouse cinema from the late 1940s is a museum of old film equipment.

Legend has it this spring formed at the spot where a medieval Swedish king was killed.

Uppsala's adorable feline sign celebrates a popular children's book set in the Swedish city.

Several cannonballs of mysterious origins decorate two buildings in Stortoget's main square.

A golden plaque marks the site of the mysterious unsolved assassination of the former Swedish prime minister.

Sound travels strangely in this underground whispering gallery.

This giant subway sculpture celebrates the fruit that inspired the theory of gravity.

Stockholm's narrowest alley is barely over two feet wide.

Now a hotel, this former bank was the site of a robbery that spawned a psychological phenomenon.

It houses the remains of a 17th-century version of the Titanic.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

An abstract representation of weather in Sweden.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

A 130-year-old urinal is the oldest of Stockholm and perhaps all of Sweden.

Stockholm's tiniest statue is of a small boy looking at the Moon.

A concrete mushroom that divided Stockholm residents for nearly a century.

Before this rocky hill was home to a chapel, it was used as a lookout by Romans and Moors.