Charlestown sits along the Connecticut River in Sullivan County, home to the reconstructed Fort at No. 4, a colonial-era frontier settlement turned living history museum. The town's Main Street runs parallel to the river, lined with historic homes and civic buildings.

The Connecticut River provides fishing and paddling access, while Fort at No. 4 draws visitors interested in the region's colonial history. Charlestown's rural surroundings include farmland and forest typical of the upper Connecticut River Valley.

Housing in Charlestown remains affordable relative to towns further up the valley near Hanover, drawing families and retirees seeking small-town, river-valley living. The town's economy leans on agriculture, small local businesses, and proximity to Claremont for larger employment.