Antwerp is the second city in Belgium and is a very beautiful and nice city to go for a weekend. Also the city has one of the biggest ports of Europe and the world and it is just like Rotterdam (which has the biggest port of Europe) a main centre of ships arriving to Europe, commodities, consumer products etc.
Antwerp has just like Amsterdam a big Red Light district, Brussels as well. It is funny Holland is so well known for the Red Light districts, especially in Amsterdam, while Belgium also has good possibilities for this, but is not famous for it.
Shopping is good as well in Antwerp and many people from Holland go shopping to Antwerp while it is close by, better quality and the people of Antwerp are very polite and friendly, which is nowadays difficult to find in Holland.