For all who search the "Our Little Town"-Letter (german: Unsere kleine Stadt), it's not by the beach, as it is written on several pages.
The correct reference is as follows:
Close to the police parking lot, there is a square with a cannon. It is the place where you've found a Flame and the Armaments History Plaque. Reach the damaged wall and use: remove. Head left through the small corridor. At the end of it, you will find: Our Little Town.