One last note: The castle is closed on Mondays.

The original interiors of the castle were largely destroyed by fires in 1595 and 1702, and by Austrian occupation when, in the early 19th century, the castle was used as a barracks for the occupying forces. The castle was repurchased by the Poles at the end of the 19th century and was restored by the architects Zygmunt Hendel and Adolf Szysko-Boluisz in a process which took 50 years. The interiors are now open to the public from around 9:30am to 4pm every day except Monday.

The State Rooms can be visited and have been restored to their early 16th-century glory, just as they would have appeared during the reign of Sigismund Augustus. The highlight is the Diet room. It has a coffered ceiling and contains 30 of Sebastian Taurach's original 194 carved wooden likenesses of the human head (including one that was gagged after apparently making an impromptu remark during one of the king's addresses).

There are also a number of rooms restored to the way they would have looked in the 17th century, during the reign of Sigismund II Vasa. Following the 1592 fire, the Italian architect Giovanni Trevano remodeled the rooms, the highlight of which is the Bird room featuring portraits of the Vasa dynasty.

The Royal Private Apartments are accessible on organised tours only. The English language tour leaves at 12:10pm and costs 18 zloty; these rooms are largely how they appeared after the remodeling work (which took place after the last great fire in 1702), and still contain many original features. The rooms contain a good collection of glass and silverware, and there is a particularly fine collection of tapestries.

The State Rooms are a joy to wander around, although they can get a little crowded with tour groups. The organised tour of the apartments, on the other-hand, is inconvenient, overpriced, and doesn't really add much to the experience.