Originally posted by xonox
... A "Kontor" was not used as a simple Storage-House but to make it possible for a special group of traders ("Gilde") to control the availability and the price of urgent goods of the medieval urban Market. ...
I understand more now.
English guild = an association of men with common aims and interests; especially a medieval association of merchants or craftsmen. The building they used = guild-hall.
The only problem I have with kontor = branch office is that such implies that there is a main office somewhere.