Architect Philip Mastrin designed The Caplen House for Mr & Mrs Harry Caplen in 1957. While Philip Mastrin designed a number of commercial buildings in Philadelphia, this home is one of his few residential designs.

Mastrin’s modernist commercial designs include the Cayuga Bank office building (now El Vez Restaurant) at Sansom and 13th Streets, one of the few surviving buildings from the bank known for its modernist branch designs. In 1950, Philip Mastrin remodeled the Mayfair Theatre on Market Street with an iconic new facade of baked enamel and glass. Mastrin also designed the former Feinberg & Sons storefront at 6324 Woodland Ave in 1957, an increasingly rare example of midcentury modern vernacular commercial design.