Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

This spectacular track has run continuously since 1882.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

A shining memorial to a Belgian hero is said to bring luck to anyone who touches it.

A little sculpture with a large wardrobe.

Amsterdam's Red Light District leaves little to the imagination.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

This stunning iron gate designed by Modernist architect Antoni Gaudí is filled with mythic symbolism.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

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

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

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

A symbol for the opposition to nuclear power around the world.

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

Old Danish castle immortalized in Shakespeare's Hamlet.

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.

This quirky UFO-shaped curiosity is often mistaken for the airport’s control tower.

Behind one of the world's most impenetrable vaults is a massive collection of retail silver.

It's a mystery why these remains were found with no traces of their bodies in sight.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.