The mansion was listed on the National Register of Historic Places in 1974.

The three-story mansion was designed in the Gothic Revival style by renowned nineteenth-century architect Frank Furness as a residence for William Rhawn, a successful Philadelphia banker.

It was completed in 1881 and named after John Knowles, the great-grandfather of Rhawn's wife.

It later served as the residence for Robert MacKay Green II, who was the son of Robert MacKay Green I, who invented ice cream soda in 1874.

The first fundraiser held at Knowlton by Conroy Catering was for former State Representative Chris Wogan in December 1997.