The nearest airport is in Brussels Airport (BRU), located 7.8 mi (12.5 km) from the city center. If you're unable to find a flight that fits your schedule, you might consider flying into Charleroi (CRL-Brussels South Charleroi), which is 29.5 mi (47.4 km) away.
Consider catching the metro at Square du Centenaire Tram Stop or Exposition Tram Stop to more easily navigate the city.