D.D.
The zoo - penguins, butterflys, giraffes, amphibians, reptiles and polar bears are all inside. The Henry Ford Museum. The Detroit Science Center. The Ann Arbor Hands on Museum. We have memberships to all of these since our daughter was a baby, she is now 4 and we just took her to Cranbrook Science Museum, she loved the dinosaurs and the rocks but it may be too old for your 3 year old. Have fun.