How can you get in the Thorne room from The land of Dragons in Kingdom hearts 2?

To access the Thorne Room in The Land of Dragons in Kingdom Hearts 2, you must first complete the main story events in the area. After defeating the Boss in the Imperial Square and obtaining the keyhole, you'll gain the ability to enter the Thorne Room. Look for the entrance on the upper level of the palace, and proceed inside to explore this unique location.