Source : Webster's Revised Unabridged Dictionary (1913)
Rathskeller \Raths"kel`ler\ (r[aum]ts"k[e^]l*l[~e]r), n. [G.,
also {ratskeller}, prop., town-hall cellar.]
Orig., in Germany, the cellar or basement of the city hall,
usually rented for use as a restaurant where beer is sold;
hence, a beer saloon of the German type below the street
level, where, usually, drinks are served only at tables and
simple food may also be had; -- sometimes loosely used, in
English, of what are essentially basement restaurants where
liquors are served.