Diners in and around Lowell National Historical Park. Arthur's Paradise Diner on Bridge Street even serves traditional mill worker sandwiches.
There's a large variety of more typical 50's style diners for example Four Sisters Owl Diner. One could make a study. They're interesting to see from the outside once you've had enough to eat.

Of course the mills were still operating in the 50's so the park has some worthwhile exhibits. Come on a nice day and walk around, lots of 50's architecture like https://www.google.com/maps/@42.644723,-71.3136828,3a,36.2y,341.93h,95.74t/data=!3m7!1e1!3m5!1s2_C5B3_S00wMvQ4izfrKDg!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3D2_C5B3_S00wMvQ4izfrKDg%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D214.984%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192