Berlin and Brandenburg were not always separate and they might not stay separate (https://de.m.wikipedia.org/wiki/Berlin-Brandenburg https://de.m.wikipedia.org/

Berlin and Brandenburg were not always separate and they might not stay separate (https://de.m.wikipedia.org/wiki/Berlin-Brandenburg https://de.m.wikipedia.org/wiki/Berlin-Brandenburg), but that is semantics. Brandenburg is a very low density area (85/sqm) surrounding Berlin (4227/sqm). It might be a problem politically but the space is there. Other cities are surrounded by areas of similar density, and cannot expand. Brandenburg has a lot of space (enough for a gigafactory) :) https://en.m.wikipedia.org/wiki/Brandenburg https://en.m.wikipedia.org/wiki/Brandenburg https://en.m.wikipedia.org/wiki/Demographics_of_Berlin https://en.m.wikipedia.org/wiki/Demographics_of_Berlin