This state hosts the headwaters of three great castle-bearing rivers either at its border or withing the state. The Rhine River actually starts across the border in Switzerland, fed by the Swiss river Aare, but it quickly runs north, away from Switzerland. The Donau and the Neckar rivers begin collecting water around the city of Villingen-Schwenningen in southern Baden-Wurttemberg. The Neckar flows north to eventually meet with the Rhine at Mannheim. While the Rhine is well known for its massive castlesfarther north, the Neckar, east of Heidelberg, is a more personal, fun way to discover castles. These are smaller that the castles of the famous robber barons along the Rhine, but equally interesting. At one point along the Neckar you can see five castle at once. Meanwhile, the Rhine along the French border is surprisingly lacking in castles that I have been able to locate. The Donau (Danube) has several, even before the river gains much width or depth.