Royal Wawel Castle – one of the biggest tourist attraction in Poland – offers free admission this month. You can save some money and visit for free State Rooms, Crown Treasury, Armoury as well as exhibitions: Acquisitions 2012 and Leonardo da Vinci: “Lady with an Ermine” and The Lost Wawel. Before visiting, you need to collect your free tickets from the Visitors Center which is open Tu.–Sat.: 9:15 a.m.–2:45 p.m., Sun.: 9:30 a.m.–2:45 p.m. Be careful! Wawel Castle (as well as almost all the other museums in Krakow) are being closed on 11th of November (Independence Day and Bank Holiday in Poland).
You can find more info on official website.