sentences:  The estate was acquired by General Henry du Pont in 1866, and between the time of purchase and 1875 he expanded the estate's size to .After du Pont's son, Henry A. du Pont took over the estate in 1875, he continued to expand the estate until it was over .In the mid-1800s, the du Ponts hired Italian masons to build stone walls around much of the property that is today part of the park.