I have a number of ancestors who are supposed to have been born in Heinstadt (or Hennstadt or Heimstadt) Prussia. I cannot find any such place. It should be somewhere in Kreis (District) Prenzlau, but I've found nothing. I have one thought. "Hein stadt" in German means "home town". Could this mean that the person's home town (ie. town of origin) was in Prussia, without intending to name the actual town?
Neil Renaud (whose great-great grandfather Friedrich Renaud is supposed to have been born in Heinstadt in 1867)