Spires or Speyer, an old German town on the left bank of the Rhine, in the Palatinate, 14 m. SW. of Heidelberg, the seat of a bishop and with a cathedral, of its kind one of the finest in Europe, and the remains of the Retscher, or imperial palace, where in 1529 the Diet of the Empire was held at which the Reformers first got the name of Protestants, because of their protestation against the imperial decree issued at Worms prohibiting any further innovations in religion.