The Swedish flag over this small naval fort signals that the nation is at peace.

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.

Stockholm's deepest subway station is also a stunning ecological wonder.

It houses the remains of a 17th-century version of the Titanic.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The widest natural waterfall in Estonia is a sight to see in all seasons.

The oldest continuously operating pharmacy in Europe.

First point in the Struve Geodetic Arc, a 19th century undertaking to measure the Earth's size and shape.

The original home of the Lego has a huge amusement park dedicated to the iconic plastic toy.

Four alabaster giants contemplate the tides on the shore of Denmark.

Old Danish castle immortalized in Shakespeare's Hamlet.

A natural wonder in south Denmark.

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

Also known as Napoleon's Canal, this waterway was created on the orders of the general, and construction was interrupted by Waterloo.

After the construction of a nearby cathedral obstructed the view, the oldest belfry in Belgium was more than doubled in height.

Relics from as far back as the 16th century are on display in a city known for its playing card industry.

A whimsical bridge uses saxophones to pay tribute to two great men and the European Union.

The bronzed skull of a beheaded traitor was affixed to the city gate in the 17th century.

Housing the groundbreaking maps and globes of Gerard Mercator.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.