The earliest newspaper record I can find for Mr. Hero actually lists 2 locations in 1968 - a want ad for “Sandwich Boys” at Mr. Hero Jumbo Submarines, 4918 Memphis Ave. and 4143 Lorain Rd. The Memphis address is still a Mr. hero, so if that is not the original, it’s probably the oldest.
All this talk of pizza reminded me that I‘ve been to the original Pagliacci Pizza on the Ave (University of Washington). It opened in 1979 and closed in 2018. According to Wiki there are currently 26 locations.
I’ve often eaten at the first Common Man restaurant in Ashland NH. It is still operating out the same building, though it’s been expanded and modified a lot. They have about a dozen other establishments in NH.
I’ve driven past the original Der Wienersnitzel on PCH (in Wilmington or Torrance, I think) on several occasions. But I’ve never stopped. It’s not one of the iconic A-frame buildings.