Europe's official "zero-level," the equator of elevation.

This 1920s Amsterdam neighborhood was built as a giant experiment in concrete construction.

Sail in for a ’dam good slice.

This museum inside Amsterdam's largest cemetery explores how people deal with death.

It's forbidden to dig within this ancient Roman fort hidden beneath a playground.

A striking memorial to the Jews of Leiden who were murdered during World War II is scattered throughout the city.

This early 19th-century graveyard is the final resting place of Vincent van Gogh's mother.

A modern reimagining of a medieval city gate.

An early 19th-century English style garden hidden in the Rotterdam cityscape.

Sweden's first electric elevator remains hidden within a fortress-like building.

Stockholm's last remaining paternoster elevator.

Tucked away in a downtown Stockholm park are the remains of a World War II defense position.

A steel paper plane is all that remains of a crashed aircraft that caused an amazingly small amount of damage.

This grisly exhibit houses skeletons and weapons from a devastating 14th-century clash.

Although rarely used, there is still a hidden room for the royal family at the Stockholm central station.

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

"Only the dead get off at Kymlinge."

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

A rare surviving Victorian greenhouse designed specifically to house giant water lilies.

No one knows who's responsible for decorating this tunnel with stuffed animals, but the people love it enough to protest their removal.

Early habitat dioramas and home of the elusive gaff, the skvader.

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

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