a VirtualTourist member
Which airport is the closest to Lier?
Antwerp airport at Deurne
but even if you would come from Brussels, public transport is easy.
Antwerp airport is only small one, not all flights land there.
if you arrive in Zaventem in Brussels you can take a transfer bus to Antwerp or you can take a train. From there you can have connection by bus or train to Lier (train is fastest).