This talk examined the great Victorian era mansions on Philadelphia's Main Line. It focused on those built for the Baldwin Locomotive Works partners, Pennsylvania Railroad officers, and leading industrialists and manufacturers. Architects featured include Furness & Evans, T.P. Chandler, Wilson Brothers, William L. Price, and G.W. & W.D. Hewitt.

Jeff Groff retired in 2021 as Estate Historian at Winterthur Museum, Garden & Library. He also had served as Director of Public Programs, and then as Director of Interpretation. For sixteen years he was Executive Director of Wyck Historic House and Garden in the Germantown section of Philadelphia. He directed the Osterville Historical Society on Cape Cod, and early in his career was Registrar/Asst. Curator at the Philadelphia Maritime Museum (now Independence Seaport). A graduate of Bates College where he majored in history, he holds an MA from the Winterthur Program in Early American Culture of the University of Delaware.

For over forty-five years he has studied and lectured on American country houses and gardens, particularly those of Philadelphia's "Main Line" and surrounding areas, with an emphasis on country life and sports, and gentleman farming.

He served as co-curator of Winterthur's very successful exhibitions "Costumes of Downton Abbey" and "Costuming The Crown."