The heart of Krakow is the Rynek Glowny. At 200m by 200m it is the largest market area of any European city. Its bulk is broken up though by the Cloth Hall (Sukiennice), the porticoed building at its heart. Now it is a charming and echoing tunnel lined by stalls selling souvenirs. Be sure to shop around, as chances are you can find the same thing at different prices. I would personally recommend the little trees made from twisted wire, with droplets of amber for leaves, and the porcelain tankards. I bought one for my father, and he now refuses to drink out of anything else! Whilst browsing the puppets, icons and (sadly) fur rugs, don't forget to take a look up at the ceiling, where you can see the coats of arms of the towns that historically traded with Krakow.
The most eye-catching site in the square though is the tall and narrow Church of St Mary whose twin towers soar to the north-east. Inside are some spectacular frescoes and stained-glass, but pride of place is the breath-taking altar-piece. The triptych, from the workshop of the justly famed 15th-century master Veit Stoss, is the largest wooden Gothic altar in Europe. Sit and spend your time examining its intricate workmanship.
Try to time your visit, as every hour on the hour a fanfare is blown from the highest of the church's two towers. Know as the Hejnal, this is to Poland what the bells of Big Ben are to Britain, and is still broadcast over Polish radio and TV every noon. The horn stops suddenly mid-note - this is in remembrance of the guard who blew the warning of an approaching army and was slain by a Tartar arrow.
Restaurants surround the main square. In my experience the food isn't much cop though (see my reviews of Sioux and Faust). Better (and cheaper) is to visit any of the stalls in the market for a Polish sausage, a pork escalope, or a bigos - all served with pickled cabbage. During the Christmas markets your choice is even more plentiful, with candies and mulled wine also on offer. There are often street entertainers (in July I visited during a street theatre festival), antiques stalls selling Soviet militaria, or Christmas stalls selling everything you might need to celebrate a joyeux Noel, from presents to candles, from decorations to trees.
Finally, to the South-east there stands a solitary belfry, the only remnant of the 14th-century Town Hall. During summer you can climb the spiral staircase to get a birds-eye view over the square - truly an unforgettable sight!