Zagreb has many different museums, from those dedicated to the greatest artists, contemporary arts, to illusions and torutre. With so many of them, it’s hard to know where to go. My recommendation is FERDINAND BUDICKI AUTOMOBILE MUSEUM.
The Museum exhibits cars, motorcycles, bicycles but also organizes various thematic workshops. In this museums you and your kids can see what cars looked like ages ago.
See on google map how to get there. Use a tram number 2 or 6 from the main square.https://www.google.hr/maps/place/Muzej+Automobila+Ferdinand+Budickifirstname.lastname@example.org,15.9967006,17z/data=!3m1!4b1!4m5!3m4!1s0x4765d64dac3cf977:0xedfcb26da32a6055!8m2!3d45.8085373!4d15.9988893