I wasn't sure what to think when I first saw a picture of the Atomium in a Belgium guidebook, but it turned out to be one of the coolest kitschy tourist attractions I've ever visited.
The Atomium was built for the World's Fair hosted by Brussels in 1958. It's not quite as famous as other monuments like the the Eiffel Tower and Space Needle, built for similar expos, but in some ways it's far more intriguing.
Visits start with an elevator ride to an observation deck. After returning to the ground floor, visitors explore remaining levels of the Atomium by escalator and stairs. The exhibits inside focus on the history of the Atomium and on Belgian design. The exhibits aren't always thrilling, but there is absolutely nothing like spending a couple of hours wandering around inside a giant metal atom.