Withdrawing to take a bath, during the Renaissance princes and princesses recovered and strengthened their health in order to be able to fulfil their duty as good rulers. Thus, many castles in the Holy Roman Empire had splendid bathrooms and were decorated as grottoes and related to gardens, which were themselves zones for withdrawal. Most courtly Renaissance bathrooms have disappeared and are only known through written sources, but those built for the House of Wittelsbach, which ruled over Bavaria and the Palatinate, left many traces at the castle of Trausnitz in Landshut (Lower Bavaria), at the castle of Neuburg on the Danube and in the Hortus Palatinus in Heidelberg. This article deals primarily with the Trausnitz bath and garden, built for William V duke of Bavaria in the 1570s and which also served as preparation for the famous grotto of the Munich Residenz. Moreover, a drawing by Friedrich Sustris, preserved at the Staatliche Graphische Sammlung in Munich, is shown to be a study for the decoration of the Trausnitz bath.