On his widow's death Saint Anne's Park passed to Algernon's cousin Rev. Benjamin Plunket former Bishop of Meath, who sold most of the estate to Dublin Corporation in 1937, keeping Sybil Hill as his residence. The corporation has preserved much of the estate as one of Dublin's most important public parks, though the house itself burnt down in 1943, with the remaining lands used for housing. The outcome of Ardilaun's extensive tree plantings came into focus a century after his death, when in 2019 the park was given Green Flag status, and was listed as one of the world's top five urban public parks.