Memorial Hall. Lovely illustrated design "One of the Six Buildings of the Centennial Exposition" on 3Ā¢ Postal entire to Ohio, postmarked with Philadelphia cds & segmented cork, corner card with red sender's printed address, reverse with red & black printed advertising for "Tin Plates", slightly reduced at right, Extremely Fine; a pretty cover. EstimateĀ $100 - 150. $0 (Image)