The place is within a mile of my home, but I have not been there yet. I would to go someday. Two of the boys in the family worked on the plumbing during construction and besides talking about all the pipe they were running they constantly talked about the size of the layout. It is a G scale layout and I believe a lot of people belonging to the Greater Cincinnati Garden Railway Society help with the layout construction, etc..
http://www.gcgrs.org/
They advertise on thier website as it being the worlds largest large scale layout. I have heard there is a lot of interaction features for the kids.
The following is the link for "Cincinnati In Motion", the S scale layout at the Cincinnati Museum Center At Union Terminal modeling Cincinntai from 1900 through the 1940's with working trains, streetcars and inclines. There si a video in the link.
http://www.cincymuseum.org/explore_our_sites/cincinnati_history/cincinnati_motion/