Würzburg is a city in the region of Franconia which lies in the northern tip of Bavaria, Germany. Located on the Main River, it is the capital of the Regierungsbezirk Unterfranken. The regional dialect spoken by people in Würzburg is Franconian. Würzburg is approximately 80 minutes train journey from Frankfurt, and almost an hour from Nuremberg. Distances to the nearest cities by motorway: Frankfurt 115 km, Nuremberg 115 km, Stuttgart 150 km, Kassel 215 km. By 1000 BC a Celtic fortification stood the site of the Fortress Marienberg. It was christianized in 686 by the Irish missionary Kilian, and the city is first mentioned as Vurteburch in 704. The first diocese was founded by St. Bonifatius in 742. He appointed the first bishop of Würzburg, St. Burkhard. The bishops eventually created a duchy with its center in the city, which extended in the 12th century to Eastern Franconia. The city was the seat of several Imperial diets, including the one of 1180, in which Henry the Lion was banned from the Empire and his duchy was handed over to Otto of Wittelsbach.