Lodz is an interesting place that is worth spending a day in if you are in Warsaw.
Although it is Poland's second largest city, it is not like krakow or Gdansk. In fact the outskirts of the city appear to be rather tatty, run down and depressing.
That said, Piotrkowska, the main and only street, is glittering with life with a diverse range of cafes and bars. For those interested in jewish history, Lodz is an essential place to visit with its Jewish Ghetto and impressive Jewish cemetry.
Lodz is also famous for its film school where Roman Polanski once studied. To Poles, it is known as HollyLodz and a Polish hall of fame can be seen outside the Grand Hotel.