I'm staying in Brussels for a while and wanted to ask if there is interesting places I could visit on the weekends or for one day trip?
The less obvious daytrips would be to Dinant (a gorgeous little town), Aachen (beautiful German city that was Charlemagne's favourite residence), and Leuven (beautiful old town with a lively nightlife and the home of Stella Artois, etc.).
And finally, Brussels is so well-connected to the rest of Europe that you can easily do weekend trips to Amsterdam, Paris, Cologne, Luxembourg, London and many others. Just be sure to book anything on the Thalys/Eurostar high speed trains well in advance to get the best deal!
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If you're into street art or urban adventures, I would also highly recommend going to Doel, a ghost city where some of the best street artists in the world got to chance to show their talent on the abandoned houses. The people of this town were forced to leave their homes many years ago, because of an expansion project of the port of Antwerp, which didn't happen yet.