The venue is the main lecture hall on the second floor of the Mathematical Institute of the University of Cologne, the adress is:
...by plane: Cologne-Bonn airport CGN and Dusseldorf airport DUS are both
well-connected to the main train station in Cologne (Köln Hbf). For intercontinental flights also Frankfurt airport FRA
is convinient. There are ICE trains to Cologne main station or Cologne Deutz taking less than 60 minutes.
...by train: Cologne main station (Köln Hbf) and Cologne Deutz are both in the city center. More information and tickets can be found here.
...from Neumarkt/Rudolfplatz the busses 136 and 146 go to the stop "Hildegardis Krankenhaus" every 5-10 minutes.
This bus stop is 2 minutes walking distance from the institute. Also walking from Rodulfplatz is possible and takes about 20 minutes.
...from Ehrenfeld the bus 142 goes to "Bachemer Strasse" every 20 minutes, which is about 5 minutes walking distance from the institute. Walking from Ehrenfeld takes about 30 mimnutes.
...from Heumarkt or Deutz the closest tram station is "Weyertal" where the line 9 stops. This is about 10 minutes from the institute.