William Plankinton Mansion, 19th century stone mansion in Milwaukee, United States.

The William Plankinton Mansion was a Victorian residence at 1529 W. Wisconsin Avenue in Milwaukee, designed by Edward Townsend Mix and built in 1876. Its exterior had a marble facing with a lion's head ornament; inside, ornate woodwork ran through the rooms and a stained glass window lit the stairwell.

John Plankinton commissioned the mansion in 1876 as a wedding gift for his son William and Mary Ella Woods. The residence exemplified the grandeur of wealthy Milwaukee family homes built during that era.

The mansion stood among the grand homes that wealthy Milwaukee families built along Grand Avenue during the late 1800s. It represented the architectural taste and social standing of the city's wealthy class at that time.

The building was sold to Marquette University in 1918 and later served as a hospital annex for patient care. Visitors should know that the structure no longer stands and exists only through historical records and documentation.

The commission was not created by this mansion's 1969 demolition. It followed the 1980 demolition of the Elizabeth Plankinton House, built across the street for William's sister, which was removed under much protest and led to the City of Milwaukee Historic Preservation Commission in 1981. The William Plankinton Mansion itself had been sold to Marquette University in 1918 under a clause requiring demolition by 1920; a legal loophole temporarily saved it.