Ptuj Castle crowns the hill above the old town and has been in some form of use since Roman times — the hill was a fortified point even before Poetovio spread around its base. The current structure is largely Renaissance and Baroque, with a handsome arcaded courtyard at its heart.
Inside, the Regional Museum occupies the castle's rooms and holds four strong collections: musical instruments, period furniture and weapons, a gallery of paintings, and a large collection of traditional carnival costumes — the masks and sheepskin suits of the Kurent figure, which chase away winter during Kurentovanje. The costume collection alone is worth the entrance fee. The castle terrace gives one of the best views over the Drava and the surrounding wine hills.