Wow, that's very interesting about Berlin name origin!!!
The origin of the name Berlin is unknown, but it may have its roots in the language of West Slavic inhabitants of the area of today's Berlin, and be related to the Old Polabian stem berl-/birl- "swamp". Folk etymology connects it to the German Bär, a bear, and a bear appears in the coat of arms of the city.
@Dervan, nice map. From where do you dig those stuff from? you have a great stash of maps as i have seen from the last few months