The Princesses, Mickey and Minnie Mouse meet at the Town Square Theater practically all day. There is a FastPass service offered for those who wish to come back later.
Check on the day of your visit for exact times.
Town Square Theater replaces (and utilises) the former Exposition Hall building that sat for many years practically unoccupied.
There used to be an actual movie theatre (actually, there were two!) in the back area, where Guests could cool off from the hot Florida sun. It would continually screen classic Disney cartoons.
We personally used to love Expo Hall, as random characters would show up there quite frequently, and being inside and secluded, you would be able to get some neat characters with almost no waiting.
Town Square Theater was installed to relocate Mickey and the Princesses once they were evicted from Toontown (to become the New Fantasyland).
It is a neat location, but there was something more enchanting about meeting Mickey at his house, and having a real movie theatre on Main Street.