Zeil
The Zeil is the main shopping street in Frankfurt and in fact one of the most frequented shopping streets in Europe. The area features department stores such as Galeria Kaufhof and Karstadt, shopping complexes like the Zeilgalerie (http://www.zeilgalerie.com/) and the new MyZeil (http://www.myzeil.de/inde...) architecture!, and many other shops. Also check out some of the surrounding streets, e.g. LiebfrauenstraÃe, SchillerstraÃe, Kaiserstrasse. Head to the GoethestraÃe for upscale shopping.
Frankfurt is a great place for shopping, as it caters both to tourists and to the local population, so you can find anything from haute couture to ridiculously cheap, and most of the shopping possibilities are located in the centre. The majority of shops are open until 8PM, though some of the larger stores downtown may close at 9 or 10PM. In general, shops are closed on Sundays.