This mysterious hilltop collection of Druid carvings isn't quite what it seems.

Legend says this little-known stone circle is formed from people petrified as punishment for dancing on the Sabbath.

Catacombs turned marketplace.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

The design of this seemingly translucent two-story tower in northwest Cambridge was inspired by an optical illusion.

Cambridge’s century-old outdoor swimming pool is tied for being the longest pool in the United Kingdom, but it is also unusually narrow.

Originally meant to hold a statue of King William IV, this support sat empty for years. Today, it hosts a rotating cast of public artwork.

A quartet of tiled art pieces adorn the floors of this prestigious art museum.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

The art museum is decorated with creatively remodeled pre-Nazi swastikas.

Site of the first radio and telephone broadcasting companies in Copenhagen.

Nordic giants resurrected from the sea and restored to their former greatness.

This contemplative sculpture made out of old machine parts is meant to be the first in a series of sculptures around the world.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

A little-known cafe in an old copper bridge tower with 360-degree views of the harbor.

This sublime architectural marvel is a rare example of an expressionist church.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Beneath Denmark's Højbro bridge, a bronze merman and his seven sons forever mourn for the mother and wife who left them for land.

There are hidden patterns on the subway seats of some Stockholm metro cars.

A traveling Bronze Age sacrificial stone that was used to honor elves, fairies, and other woodland spirits.

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

Finally reunited, the three effigies now stand in a museum courtyard.

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.