Antwerp has lots to see, it's a short train ride from Mechelen (or Bruxelles), and it starts with a beautiful train station:

I started with Chocolate Nation next to the train station (click me for blog):

After that, lots to see in town, Museum aan de Stroom has a bit of a random and weird collection on multiple floors, but at great view:

Waking pseudo-randomly through Antwerp, plenty of things:

From there, I went to the Plantin Moretus Printing Museum (click me for blog):

And still plenty of daylight and sights to finish the day in town:

And that was it. Antwerp has plenty to things to do. If you want to be thorough and go at a reasonable pace, 1.5 to 2 days isn't too much, but it can mostly be done in a day, like I did here.