Würzburg lies along and is an inland port of the canalized Main River, about 60 miles (100 km) southeast of Frankfurt am Main. The site of a Celtic settlement, it was first mentioned as Virteburch in 704. A bishopric was established there by St. Boniface in the early 740s, and the bishops had acquired ducal authority over eastern Franconia by the 12th century. Repeated revolts against the power of the bishops resulted in the citizens’ final submission to their authority in 1400. Several imperial diets (assemblies) and councils were held in Würzburg, including one in 1180, when Henry the Lion was placed under the imperial ban and the Bavarian duchy was taken from him and given to Otto, a member of the Wittelsbach family. Würzburg progressed under Bishop Julius (1573–1617), and much building was commissioned by the bishops of the Schönborn family in the 18th century.