Founded in 1137 following the Treaty of Mautern, the partially constructed Romanesque church was solemnly dedicated in 1147 to Saint Stephen in the presence of Conrad III of Germany, Bishop Otto of Freising, and other German nobles who were about to embark on the Second Crusade. Although the first structure was completed in 1160, major reconstruction and expansion lasted until 1511, and repair and restoration projects continue to the present day. From 1230 to 1245, the initial Romanesque structure was extended westward; the present-day west wall and Romanesque towers date from this period. In 1258, however, a great fire destroyed much of the original building, and a larger replacement structure, also Romanesque in style and reusing the two towers, was constructed over the ruins of the old church and consecrated 23 April 1263. The anniversary of this second consecration is commemorated each year by a rare ringing of the Pummerin bell for three minutes in the evening.