mcall.com — By Devon Lash, Of The Morning Call 10:21 p.m. EST, February 22, 2012 When Philadelphia painter David Ohlerking sought inspiration in Allentown, he went to Pizza Mart. The Hamilton Street restaurant isn't the most obvious muse downtown. The dusty storefront overlooks the bubble gum-speckled sidewalks beneath weathered green windowpanes and the familiar red overhang next door.