More than 5,000 years old, D27 is the largest dolmen in the Netherlands and was already standing long before Stonehenge and the Egyptian pyramids were built.

When the water level in the Danube in central Budapest is low enough, there is a secret site telling the history of one of the most iconic bridges of the city.

Originally planted by the ancient Carthaginians, this sprawling palm grove is one of the largest in the world.

The second largest palm grove in Europe was planted during Moorish times and has been largely unchanged since then.

Painting of this dam or weir seems to be a tradition

This fake airfield was built as a decoy to protect a real airport from the Allied Forces.

This beautiful early 20th-century military barracks now has numerous more peaceful uses

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

Bacteria and algae give the salty water its bubblegum hue.

The highest point in the Kingdom of the Netherlands is on a remote Caribbean island atop a dormant volcano.

This interactive sculpture allows visitors to leave a message in case a friend passes by.

The legendary giant's severed hand sits on Antwerp's popular shopping street.

A storm shelter built for survivors of shipwrecks.

The first park built over a freeway is a brutalist masterwork.

This hidden treasure is the world’s oldest active geocache.

This popular tourist cave was ignored for almost 200 years before being mined into an attraction.

An abandoned lighthouse located on the cliffs of Barbados.

Under the desolate and windswept northern coast of Barbados stands a small oasis filled with sea anemones.

A preserved ancient Marshall Britannia steam locomotive on display at a train station.

A beautifully preserved and hidden 16th-century alleyway, tucked behind an unassuming door.

The remnants of a refugee settlement for Belgians during WWI.

Oldest World War 2-themed museum in Western Europe.

A remnant of the Franco-Prussian War, lodged in the city's walls.

One of Amsterdam’s most popular cultural and recreational complexes is on the site of a former gas works.