Evening commuters are silhouetted in the oblong windows of the train. Below, a festive gathering is in full swing. German police stand guard in front of the Jewish Community Centre. It is the Jewish festival of Succot - a thanksgiving for the harvest. The air rings with the sound of Klezmer music and Israeli folk tunes.
Men link arms, singing and dancing with boisterous energy.
Soon the women form their own circle alongside them, clutching toddlers in their arms - clapping and singing in the open air. Germany's Jewish population is flourishing. Few people could ever have imagined that 55 years after the end of World War II, Germany would have the fastest growing Jewish population in the world - and the third largest Jewish community in Europe. Tens of thousands of Russians have arrived from the East, whilst American and British rabbis and Jewish teachers have come from the West. I had tea with the Milysteyn family at their small apartment in Potsdam.