This small state park is the location of the remains of a village inhabited by a 200-strong community of Ancestral Puebloans in the middle of the 12th century. As well as a trail that leads past impressively realistic reconstructions (pictured) and around the actual archeological remains (known as the Coombs Site ruins), there's an excellent museum with enough hands-on exhibits to keep younger visitors entertained. There's also a gift shop and very clean restrooms!
If you go:
The museum is open all year round apart from Thanksgiving, Christmas and New Year's Day.
Links:

Anasazi State Park Museum
460 North Highway 12
Boulder, Utah 84716 USA
parkcomment@utah.gov
Mailing address:
Anasazi State Park Museum
P.O. Box 1429
Boulder, UT 84716-1429 USA
Phone Numbers:
+1 (435) 335-7308