There are two Sparkasse branches in Gummersbach center, this is one of them. I've never been inside. It's attached to the same building as the Rathaus/Townhall.
If Gummersbach has an "old town", this is it. Cobbled streets & older buildings. This is the headquaters of S&F, which Google tells me is S&F Personal Dienstleistungen GmbH
There are routes through the Forests around Gummersbach in all directions where pipes run underground. Trees have been cut down and there are lines just running up hills completely devoid of trees.