Historic Heidelberg is located on the Neckar River in southwestern Germany. It is home to Heidelberg University, the oldest university in the country. In fact, one in every five Heidelberg residents is a student. Known for its architecture, Heidelberg is home to the gothic Heiliggeistkirche church which overlooks the town square in Alstadt and the ruins of Heidelberg Castle which stands on Königstuhl hill. Built in 1751, the Heidelberg “Tun” is the world’s biggest wine barrel and sits in Heidelberg’s famous castle.