It’s ironic that one of the few parts of the august university that Count Palatinate Ruprecht I established in 1386 open to the public are these rough cells where unruly and drunken students were once incarcerated. (If laughter and screaming disrupt your sleep in an Altstadt hotel, you may wish the practice were still in force.) Prisoners bedecked the walls and even the ceilings with graffiti and drawings, including portraits and silhouettes, until the last ones left in 1914. Despite the need to control rowdiness, even the curmugeonly Mark Twain commented that “idle students are not the rule” in Heidelberg. Germany’s oldest university, officially known as the Ruprecht-Karls-Universität Heidelberg and centered around the Universitätsplatz, has produced 55 Nobel Prize winners.