Visit the ancient, mysterious Roman catacombs ... in the Netherlands.

Colorful and chaotic stacked hotel in North Holland.

This unattributed sculpture in Amsterdam is hiding in plain sight.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

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

Visitors to this Belgium graveyard are greeted by the grieving stone parents of the young men lost to war.

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

The compass on its front was a handy tool for 17th-century merchants who needed to know the direction of the wind.

This former guildhall with a bacon-like exterior is now home to a museum covering 600 years of Antwerp's musical history.

This old, abandoned hotel offers magnificent views.

Head underground and take a tour of the city's working sewer system, and see the underground river Senne, which defined Brussels for centuries before being covered in the 19th century.

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

A little sculpture with a large wardrobe.

Explore 400,000 years of humans' "battle against darkness" in this offbeat but thorough lamp museum.

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