Constructed in 1680 and moved to its current location in 1808, the Eastham Windmill is the oldest of several distinctive windmills on Cape Cod. And it still functions. It's a memorable photo opportunity at any time, but every fall on the weekend after Labor Day, it's celebrated with a Windmill Weekend featuring a parade, sand art, a car show and other amusements.
If you go:
The windmill is open so you can see it in operation in July and August only, from 10:00 to 5:00 Monday through Saturday and 1:00 to 5:00 on Sunday.
Links:

2515 Massachusetts State Highway 6
Eastham, Massachusetts 02642 USA
Phone Numbers:
Town Of Eastham
+1 (508) 240-5900
+1 (508) 240-5900