The original structure of the museum is an Italian Renaissance villa that was the former home of Oklahoma oil pioneer Waite Phillips and his wife Genevieve. Phillips commissioned prominent Kansas City architect Edward Buehler Delk to design the mansion in 1926; construction began the same year by the John Long Company of Kansas City and was completed the following year. Named "Villa Philbrook," the three-story mansion was constructed of steel and a reinforced concrete framework that resulted in minimal remodeling being required to transform the villa into an art museum. The exterior of the house is stucco that includes ground white marble in the mixture causing it to glitter. The corners are quoined with Kasota limestone, quarried in Minnesota, that resemble Italian travertine. This stonework also decorates the doors and windows. In the rear of the house, a loggia showcasing five arches with Corinthian columns, highlights a terrace overlooking the formal gardens. The roof features wide eaves and is covered with oversized Italianate tiles.