One full day in Antwerp. No car. What should we see?
What appeals to you?
https://www.ricksteves.com/europe/belgium/antwerp
I'll ask the same as Liz. I can tell you what we saw and enjoyed but my interests may not be the same as yours.
We really enjoyed the Printing Museum. Well-designed place with lots of 16th century printing equipment, artifacts and original house and workshops.
I am interested in learning about Antwerp’s history. Brief description of museums don’t say there is history information inside. So where can I find the town’s history?
I much prefer Antwerp to Brussels. History: Vleeshuis Museum, Excellent MAS absorbed the Shipping Museum, the "old port" has remants at the north side of town. (Free roof deck viewpoint) There's a Beguinhof, although I haven't been there. There is a tourist office in the old Steen (castle), which has a plaque on it about liberation by Canadian troops, I think. Not quite history, but 100 turn-of-the-century townhouses (exteriors only) in many elaborate styles are to be seen in the Zurnborg/Cogels Osy Lei neighborhood. (Tram to Draakplaats or Berchem.) The Printing museum is a UNESCO WHS site, but is a little dry. Red Star Museum about shipping history also.
If you don't feel a duty to study history, I'd go to the world-class art museum, KMSKA. They might have the most Rubens paintings on exhibit in the world, but I haven't fact-checked that idea. Just reopened after years of gut renovation. Note tidal bronze sculpture in front of the museum. Also, some Art Deco old building facades behind and to the left of the KMSKA. Disused-looking (?) colored terracotta synagogue facade also nearby.
Back to history, the small gem of an art/mansion museum Van Den Bergh has leather wallpaper and nice interiors, as does the Foundling Home, or Maagdenhuis Museum, which is also historical. Nice small botanical garden nearby.
There are plenty of historic buildings and churches, just not all together like they are in Bruges. (Antwerp is many times larger than Bruges.)
I might suggest sections of the Museum Aan de Stroom (MAS for short):
https://mas.be/en/content/welcome
Look at some of the guided tours they offer?
https://mas.be/en/guidedtours
Belgium has a rich artistic history! I would have sent you to Museum Mayer van den Bergh and Peter Paul Ruben's former home but they're both closed for renovation. You might look at the Royal Museum of Fine Arts?
Important churches: always part of an old European city's historical fabric. Try these? I'll give Our Lady of Antwerp Cathedral (Onze Lieve Vrouwkerk) an extra shoutout;; the carved choir stalls, pulpit and confessionals are stunning (!!!) and it has a number of Rubens.
https://mkantwerpen.be/en/churches/
https://www.dekathedraal.be/en
A bit more about the cathedral, and I'll encourage internet searching for even more before you go.
https://aviewoncities.com/antwerp/cathedral-of-our-lady
A must see for me was the 1930s era all wooden escalator. Another was Het Bootje, an art nouveau building. I’m sure neither is on most people’s list of things to see. We did enjoy the Church of Our Lady with its Rubens paintings, the Grot Markt, and the Red Star Line museum.