Erected in 1840 on a bluff over the Beaver River in the northern part of the borough, it has been ranked as the grandest and best-preserved 19th-century house in Bridgewater.

[3] The mansion was built for coffee entrepreneur James Arbuckle, whose architect employed the Greek Revival style of architecture.

During these years, the house was the home of a public official: William was elected to represent the 46th District in the Pennsylvania State Senate in 1890, and he remained in this position until his death.

[2]: 3  Except for a period as the home of a veterans' organization, the mansion has always been used as a residence, although would-be buyers sought to convert it into offices or a print shop.

[2]: 5 Dunlap's mansion is a three-story brick structure built on a stone foundation, with four large chimneys and a cedar interior.