Rheingauer Dom is the colloquial name for the Catholic parish church in Geisenheim, Germany. Officially Pfarrkirche Heilig Kreuz (Holy Cross), the large church in the Rheingau region is called Dom although it was never a bishop's seat. The present building was begun in the 16th century, but major features such as an expansion of the nave from three to five vaults, the towers, the organ and several altars were added in the 19th century. The parish is part of the Diocese of Limburg.