A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

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

A plaque marks the house in Stockholm where the French philosopher René Descartes lived up until his death.

A wooden street sign is the last remnant of this 400-year-old alleyway.

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

One of the world's first dedicated bank buildings in the world is now the oldest one.

A temporary art piece to celebrate LGBTQ Pride is now a permanent part of Stockholm's traffic landscape.

The scars of a remarkably organized public protest to save 13 elm trees are still visible in this Stockholm park.

Outside a Viking museum sits a modern-day runestone made by a Swedish runemaster using traditional methods.

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.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

Dedicated to the European Sinti and Roma peoples murdered during the Holocaust.

A historic fire call point.

Known simply as "The Hand," this famous public sculpture in Berlin was featured in a Depeche Mode music video.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

Berlin's old airport.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

A fascinating insight into daily life in the Eastern Bloc.

A collection of abandoned typographic signs from Berlin and beyond.

One of the world's heaviest musical instruments towers within a popular urban park.

A man's head is enshrined beneath a statue near the first building constructed for the modern Olympic Games.

The only surviving choragic monument is a trophy awarded in 334 BC for the winning dramatic chorus.

A Byzantine-era church hidden in a wooded area below the Acropolis.