The nearest metro station is Port de Namur/Naamsepoort, which is 100 metres from our office.
By airplane: take the airport-city bus. It terminates at Trone, from there you can walk for about 5 minutes. The airport-city bus journey takes about 35-40 minutes, more details here. Alternatively, take the train from the airport to Gare du Midi and from there the metro.
By train: try to get off at either the Brussels Central or Brussels Midi stations. From there take the metro to Port de Namur/Naamsepoort.