Danube conservation and touristic development of the Danube region. In medieval Regensburg, with its maintained old town, stone bridge and cathedral, the Route of Emperors and Kings begins. It continues to Engelhartszell, with the only Trappist monastery in Austria. Further highlight-stops along the Danube include the "Schlögener Schlinge", the city of Linz, which was European Capital of Culture in 2009 with its contemporary art richness, the Melk Abbey, the university city of Krems and the cosmopolitan city of Vienna. Before the Route of Emperors and Kings ends, you pass Bratislava and Budapest, the latter which was seen as the twin town
Source of the Danube above and below Tuttlingen (see also Danube Sinkhole). As a consequence, it dries up most time of the year. Near Ulm, in terms of hydrology, the Danube gets a tributary to the Iller which is more water-rich. It even gets surpassed by the Inn. The Donaubach rises on the castle grounds near the left corner of the front face of the castle Donaueschingen in a karst spring. This karst spring has an embankment of 15 to 70 l/s and enters into the Brigach after flowing 90 meters belowground. The Brigach and the Breg become the Danube after 1.5 km. The