The district is centered on the historic heart of Pittsfield encompassing a number city blocks adjacent to Park Square, which is at the junction of North, South, East, and West Streets.

When first listed on the National Register of Historic Places in 1975, the district encompassed the park and eight buildings that faced it, including the Old Town Hall, the county courthouse, the Berkshire Athenaeum, and the First Church of Christ.

[2] In December 1991, the boundaries were expanded to the area roughly bounded by East Housatonic, South, North and Fenn Streets, and Wendell Avenue, adding 39 buildings to the district.

Park Square, the heart of the city, was laid out in 1790 on land donated by John Chandler Williams.

It became a regionally important hub due to its railroad connections in the mid-19th century, and became the shire town of Berkshire County in 1868, spurring further growth.