Cylburn Arboretum (207 acres) is a city park with arboretum and gardens, located at 4915 Greenspring Avenue, Baltimore, Maryland. It is open daily - excluding Mondays-without charge. The arboretum began as the private estate of businessman Jesse Tyson, who started construction of Cylburn Mansion in 1863. The house, designed by Baltimore City Hall architect George Aloysius Frederick, was eventually completed in 1888 and remains intact, a stone structure built of gneiss from Tyson's quarries at Bare Hills, with mansard roof, tower, and an Italianate cupola. It became the Cylburn Wildflower Preserve and Garden Center in 1954 and, in 1982, was renamed the Cylburn Arboretum Association.