The biggest one – by far – is also the one closest to Brussels: Brussels Airport. The Brussels Airport looks modern and luxurious and has lots of shops, restaurants and cafes. It’s located about 15 km north from the center of Brussels, which you can reach by train, bus, car or taxi.
Traveling by bus is the cheapest way to get the city center. You can take the express line or the Bus 12/Airport Line, which runs every 30 minutes from Monday to Friday, until 8 PM. This bus will take you to the European Quarter. Another option is Bus 21. This one is a tad slower but runs in the weekends as well. It takes you to Ducale, right in the center of Brussels. Buses 471 and 272 will bring you to Brussels-North.
The fastest way to get to the center from the Airport in Brussels is the train, because by bus, car or taxi you will probably get stuck in a traffic jam. The train is a bit more expensive than the bus because you have to pay the Diabolo tax.