Krakow
Krakow is yet another of the Polish cities that had the crap bombed out of it during WW2 and rebuilt itself better than before. The old city, centered around the largest market square ("rynek") in Europe is a gorgeous recreation of the past. Attractive buildings, huge churches and literally hundreds of bars and cafes make it a great place just to wander around.
South of the old city is the Wawel, the old palace of the Polish kings, plus another huge cathedral. Well worth a look around, tours are a little pricy and limited in number. Several restaurants are located on site and the prices are surprisingly reasonable for the location.
Further south again is the Kazimierz, the old Jewish quarter. Lots of history here, apparently, for those who are interested, but I have to admit that my leg was giving me grief and I wasn't interested enough to endure the pain.
I stayed in a new hostel, imaginately name "Hostel Rynek 7", which overlooks the central rynek. Brand new, very clean, friendly staff, free wireless and internet, cable TV, nintendo and whatnot, it's a deal which is hard to beat. 55 zloty for a dorm bed, it's a great deal bt Polish prices.
