At low tide, you can see the remains of a 17th-century ship just off a Stockholm island.

The 19th-century home of Count and Countess von Hallwyl is now a museum.

The site of Stockholm's last public execution.

Part of an abandoned19th-century fortress hides in plain sight inside a modern office building.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

The narrowest street in Paris.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

Abandoned railway line circling the city of Paris.

Small Easter eggs are hidden in the ventilation holes of the city's newest trains.

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

A water reservoir disguised as a castle stands atop a hill in a park in Stockholm city.

A king's bloodstained shirt is among the gruesome collection of artifacts displayed below Stockholm's Royal Palace.

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

The oldest housing complex in Riga is a mini timeline of architectural trends.

This charming Latvian lane doubled as Baker Street on the Soviet Union’s version of Sherlock Holmes.

A preserved oak tree about 3,500 years old found in Riga, Latvia.

A stone marker and sculpture in the city of Riga stake a claim for the very first community Christmas tree.

With a design inspired by traditional Latvian textiles, this monument honors the Latvian people who suffered under Soviet occupation.

A statue built to honor the elite soldiers who fought for Latvia during World War I.

Latvia's symbolic mountain-shaped national library is home to millions of cultural tomes.