Mangialardo's on PA Ave, SE - 1953, moved to their current location in 1958. The old Italian neighborhood is gone, the Feds still come for the G-man subs...
Deli City on Bladensburg Road - at least 30 years since they settled in this once Jewish neighborhood...
Jimmy T's on East Capitol on Capitol Hill dates back about 50 years. Who cares how old it is? It hasn't changed....