The "Eleventh Arbeitstagung of the Second Series" will take place from Wednesday, May 22, to Tuesday, May 28, 2013. It will be dedicated to the memory of Friedrich Hirzebruch who started the Arbeitstagung in 1957. For this reason more lectures than usual will be fixed in advance. The speakers include Michael Atiyah, Paul Baum, Dusa McDuff, Gerard van der Geer, Nigel Hitchin, Frances Kirwan, Maxim Kontsevich, Matthias Kreck, John Milnor, Mina Teicher, and Kenji Ueno. The talks will be published in a proceedings volume. The traditional boat trip on the Rhine will be on Sunday, May 26, the reception by the Rektor in the Festsaal of the University will be on Monday, May 27.