The Grey Towers Castle is a building on the campus of Arcadia University in Glenside, Pennsylvania, which is located in Cheltenham Township, a suburb of Philadelphia, United States.

In 1881, William Welsh Harrison, co-owner of the Franklin Sugar Refinery, purchased Rosedale Hall from J. Thomas Audenreid.

In 1893, the main house of Rosedale Hall burned to the ground in a raging fire, during which the Harrison family fled to the stables for safety.

By March 1893, Trumbauer presented Harrison with plans for a grandiose mansion, inspired by Alnwick Castle, the medieval seat of the Dukes of Northumberland.

Grey Towers Castle is designed in a highly eclectic yet elegant fashion, taking inspiration from a variety of styles, periods, and buildings.

The house is built of grey stone quarried at nearby Chestnut Hill, and Indiana limestone is used for exterior door and window trim, and other elements, such as the various gargoyles.

The Library, now the President's office, and the Dining room, both on the south side of the Great Hall, contain many elements reminiscent of French Renaissance decoration.

The walnut cabinetry and plaster friezes in the Library and the columns and caryatids and strapwork ceiling in the Dining room are inspired by interiors of the Château de Fontainebleau.

It is thought that the entirety of the Mirror Room was ordered at the New York office of a French firm, then crafted in France and shipped to Glenside, along with workers, to be installed.

William Welsh Harrison died in 1927, and in 1929 Beaver College (now Arcadia University), then located in Jenkintown, purchased the estate from his widow for $712,500.

After the initial purchase of the land by Beaver College, science labs were put in this building as well as a chapel in which the chorus sang.

Blankley Hall was originally known as the gatehouse, where guests were greeted before taking the path (now the Alumni Walk of Pride) up to the Harrison's castle.

After Beaver College purchased the estate, it was briefly used as student housing, and then as office space for university employees.