Clinton P.
Yelp
This is one true gem in downtown Birmingham. Yes, the Civil Rights Museum is also wonderful, but it is so sad to visit and think of the waste of human potential that Birmingham still represents to many people worldwide. Our bad reputation is well-deserved, no denying it - we are the Ndamukong Suh of American cities.
McWane is free of such history and baggage, and really evokes the opposite emotions: it shows all kids that there is a better and brighter future out there for them if they want to learn about it. There are fish and aquatic animals in the basement, and you can pet sharks and stingrays. There is a special little section for kids 6 and under called "Just Mice Size." (hint: do not let on that you can fit into the labyrinthine climbing house! If you do, your kids will insist that you climb in with them. You don't want that, unless you really liked basic training).
There is a permanent dinosaur exhibit - who doesn't like dinosaurs? There are dozens of clever machines that teach kids some basic principles of physics. There's a show where they blow up stuff! (awesome!)
The top floor houses traveling exhibits that keep you coming back, but my kids have been going for ... well at least 10 years I think, and my older one (7th grade) just went on a field trip there to learn about forensic science - yup, genuine CSI stuff, including doing a DNA gel electrophoresis. If you already know what that is, kudos to you, but I bet you don't, even though you've seen the results many times. (hint: see http://www.innocenceproject.org)
It's much more than just a place to take the kids on cold and rainy days, especially as everyone in the Birmingham-Hoover Metropolitan Statistical Area seems to have the same idea on cold and rainy days. Between here and the Zoo, you're pretty much covered for educational kid entertainment.