Morocco’s modern capital was once a haven for Barbary pirates, who went so far as to establish a republic of their own.

The deadliest diving spot in the world is also a stunning geological marvel.

This slowly crumbling mansion was home to one of East Africa's richest and most powerful slave traders.

Freddie Mercury's childhood home is now a monument to the iconic Queen rockstar.

In Zanzibar, a historic 19th-century palace is a reminder of the world's shortest war.

This monument is a stark reminder of the horrors of the Zanzibar slave trade.

Scale model of St. Peter's Cathedral (Rome) in the middle of a small Dutch town.

A maze of crosses marks the jumbled divide between the Netherlands and Belgium.

This fairy tale forest hides scenes from some of the more obscure and bizarre Western nursery stories.

A radio telescope for listening to the stars, based in one of the cloudiest countries in the world.

This giant radio telescope would be a rusting ruin if it hadn't become such a beloved relic.

This towering church is home to a world-famous organ and a treasure trove of medieval art.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

The ruins of a medieval castle that once belonged to one of the most powerful families in the Netherlands.

Rich with fauna and flora, nature-lovers can walk across the sea at this UNESCO World Heritage spot.

Home to the world's oldest functioning orrery.

Live out your childhood construction fantasies in this one-of-a-kind gyrating hotel.

The 20-mile causeway that separates the Netherlands from the sea.

This Dutch statue is a monument to the fictional shrew who brought doom to the city of Stavoren.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

This former hydraulic laboratory is now a woodland dotted with old engineering models.

The struggle of a small Dutch island against the sea.

This artificial ring island was built to hold cubic tons of polluted dirt.

While most bridges allow roads to pass over water, this one allows water to pass over a road.