A huge covered market, housing dozens of stalls, selling a wide variety of fresh produce at very…read morereasonable prices. Just wandering through makes for a fascinating experience. It's hard to recommend just one or two vendors: the best bet is to go and decide for yourself which produce most takes your fancy. (Beware if you are a bit squeamish - the meat vendors have pigs' heads and skinned rabbits on display!).
The building itself is an impressive example of Brutalist architecture - which they've tried to tone down with a pinkish hue of paint!
On Saturdays there's a large temporary market in the adjacent square, selling all sorts of leathergoods, shoes, clothes, fabrics, bedding, plants, kitchen utensils - you name it. As you'd expect, there are bargains to be had, alongside plenty of tat, so check the quality (and beware the odd pickpocket, as it does get very crowded).