Heidelberg is a city in south-west Germany. The fifth-largest city in the State of Baden-Württemberg after Stuttgart, Mannheim, Karlsruhe and Freiburg im Breisgau. Heidelberg is part of the densely populated Rhine-Neckar Metropolitan Region. In 2011, over 149,000 people lived in the city. Heidelberg lies on the River Neckar in a steep valley in the Odenwald. Modern Heidelberg can trace its beginnings to the fifth century. The village Bergheim (Mountain Home) is first mentioned in that period, in documents dated to 769 AD. Bergheim now lies in the middle of modern Heidelberg.