Translation request

[kingtiger]

I have had this wooden plaque for several years and always wondered what it said or meant. I will post front and back and any help would be sincerely appreciated.

Mark

[tempelhof]

Sorry Mark, I did not see this earlier.

You have:

"Be proud of what German minds and German fists have accomplished. This ennobles you." or "Be proud of what German minds and German fists have accomplished as this ennobles you."
I try to put these things into English as it may have been said by an English speaker, so take your pick.

The reverse:

"Richtfest (this is an old tradition of consecrating, blessing, topping of a new structure which has just been completed)"

"Sperenberg-Heegesee ( Panoramio - Photo of Sperenberg - Heegesee )"

"3.4.1939"

"Military Building Authority (or Army Building Office etc.) in Jueterbog"

Essentially you have a plaque here which was probably hanging during a ceremony (a Richtfest) which was held on the completion of a building put up in part or in whole by a military authority.
Here in the states this would be the sort of thing you might hang at a ribbon cutting ceremony.