Visiting Shelburne Museum and one of the largest and most comprehensive collections of Americana anywhere
Shelburne really deserves at least two full days; I was only able to spend one day, but will be back. These 650+ photographs show only a small part of the collection on display. More information on Shelburne Museum is on their page on The History List.
The Round Barn, with carriages, coaches, sleighs, wagons, and other means of horse-drawn transportation.
The Circus building, with carousel animals, a 500+ foot long miniature circus parade, a 3,500-piece miniature three-ring circus, circus posters, and more.