The Red Main is the southern and longer of the two source rivers of the Main that flow through Bayreuth and plays a defining role in the geography and history of the region. It rises in the Lindenhardt Forest south of Bayreuth, near Hörlasreuth (Creußen), at an elevation of 581 meters above sea level. From its source, it initially flows southeast, then north through the Upper Main Hills and the Upper Red Main Valley nature reserve. It crosses the city of Bayreuth from east to west. Beyond Bayreuth, it is allowed to meander naturally through a wide valley. The Red Main is approximately 73 kilometers long. Near Kulmbach-Steinenhausen (at 298 meters above sea level), it merges with the shorter but more voluminous White Main, which originates in the Fichtel Mountains. From this point onward, the river is known simply as the Main. The name "Rot" derives from the reddish-brown sediments (as seen at the Bodenmühlwand) that it carries from its catchment area, which is characterized by Keuper rock. In contrast, the White Main carries lighter granite sediments.