A treehouse assailed by the elements and the government, now gone.

An amazing collection of sculptures and art.

A collection of pianos and more guaranteed to delight anyone interested in music history.

This secret gem of a toy store houses a rideable carousel populated with fantasy animals.

A folk art mecca famous among outsider art fans.

Wander through more than 20,000 square feet filled with an amazing collection of orchids.

A huge musical instrument played by the ocean.

Cat art as far as the eye can see.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

A floating cat sanctuary on an Amsterdam canal.

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.

Centuries-old bridges grown from tangled roots.

The 953 windows undoubtedly make this the world's most beautiful screened porch.