Photos

I visited a museum for Lignite (aka brown Coal).
Here we saw a lot of old machinery, buildings and photographs from the World War II period.
During and after WWII there was a shortage of fuel, so the Danes started to excavate brown coal, used for heating houses, fueling trains and other means.
Brown Coal is like ordinary black coal, but was dug near the ground surface.
The brown coal mining facillity had a bad reputation, a bit like Klondyke, for drinking, gamling, fighting etc. The mining cities were independ with own shools, churches, general stores and doctors. The people outside did have a great respect for the hard working people... and with good reason. They really liked a good fight ;-)

Also see this article from WikiPedia