I've been aiming at this one for a while. The last time I visited The World's Largest Collection of the World's Smallest Versions of the World's Largest Things, I looked ahead to see if there was a good one somewhere on my way. And sure enough, the World's Largest Model of the Solar System is in Peoria, Illinois. Well, no, that's not true. According to Roadside America, Peoria's solar system has been surpassed by one in northern Maine. They also report that one spanning England and Wales is under construction and "scheduled for completion in 2005." I did a Google search, but failed to find a report that this project was completed.
In any case, I'm in Peoria, not Maine or England, so I'll make due. The Peoria Solar System seems quite nice, although Roadside America reports that you have to be careful when you time your visit.
When we visited, we learned too late that the barbershop housing Venus was closed Sundays and Mondays.
Isn't that always the way it is....