Origin: Ger < rath (now rat) (akin to read), council, town hall + keller, cellar: because frequently located in the cellar of the city hall
See rathskeller in American Heritage Dictionary 4
Origin: German Ratskeller, Rathskeller, restaurant in the city hall basement
Origin: : German Rat, council, counsel (from Middle High German rāt, from Old High German; see ar- in Indo-European roots)
Origin: + German Keller, cellar (from Middle High German, from Old High German kellāri, from Latin cellārium; see cellar).