Most homes in the district are set back between one and from the sidewalks. The lots are relatively narrow (50–60 ft.) but deep (120–150 ft.) with ample backyards that often hold one-story frame or brick garages on an alley serving an entire block. Average density is five to seven houses per acre. This configuration — a single-family house sited close to the front lot line with a detached service building at the rear of a long backyard — is the basic lot layout of towns in central Pennsylvania. Most of the rear-lot service buildings are either small 19th century carriage barns converted to garages or 20th century auto garages, depending upon the age of the house. The carriage barns are generally wood frame while the garages tend to be brick, depending upon the building material of the house. The moderately sloping topography did little to impede local builders, who merely terraced the sites and erected stone retaining walls to hold the yards.