Creating a 3D Town to explore

I’m trying to figure out the best way to be able to create a Flash-based interactive 3D experience that allows the user to walk or drive around a town, perhaps click different links to “enter” shops, etc. The best view would be a bird’s eye 45 degree angle - so would isometric-based game controls be the way to go?

Can this be done using just Flash? Or do I need to begin learning other programs like Director - Shockwave 3D, etc. What recommendations do you folks have for creating such an environment?

Thanks a ton for your input!!