Rockingham is believed to be the second oldest house in the Millstone River Valley, its original rooms built about 1710. The house was originally a two-story, two-room frame house with a one and one-half story lean-to at its back, situated high on a rocky hillside above the river. The house and about 100 acres were purchased by 1735 by John Berrien, who later served as Somerset County Judge, Trustee for the College of New Jersey (present day Princeton University), a New Jersey Supreme Court Justice and Colony Assemblyman. He greatly enlarged the house for his growing family in the 1760s and added land gradually to total over 360 acres, making it a substantial farm appropriate for a prosperous, well-established man.