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

What looks like a birch tree smushed between two pieces of glass often confounds commuters.

This pair of unsuspecting buildings are in fact the very first modern skyscrapers in Europe.

When this 18th-century observatory's meridian was moved, it set Sweden's time back by 0.04 seconds.

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

A man has revenged his true love's betrayal through tears and stone genitalia.

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

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

The world's first invisible city square is an homage to a man who pushed the boundaries of art.

While this monument tile is shrouded in mystery it also marks the end of the longest ever human chain.

The world's second-tallest flagpole stands proud despite dropping rank.

This retro, UFO-like structure is a remnant of the Soviet-era circus.

Beatlemania is still going strong... at least in Kazakhstan.

Dedicated to the outnumbered Finnish forces who pushed back Soviet forces during the conflict.

One of the oldest structures in Helsinki is this burrow grave that dates back to the Bronze Age.

A modern tower, symbolizing the legend of a golden egg on top of the tree of life.

An entertainment center in a huge transparent tent.

Iconic pyramid from famed British architect Norman Foster designed to represent all of the world's religious faiths.

This hotel was once home to a steamliner company and became the final rest stop for Europeans heading to the New World.

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

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

A glacial pothole was once a hideout for a notorious Scottish outlaw.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

Scotland's oldest medieval bridge is also among the last reminders of early medieval Aberdeen.