What big event does the prince organize after the people have been in seclusion for five to six months what is unique about the rooms used for this event

This question refers to the story "The Masque of the Red Death" by Edgar Allan Poe.

In this story, we encounter a kingdom that has been greatly affected by a horrible epidemic. The prince of this kingdom decides to isolate himself in a castle. However, he brings several knights and ladies with him.

After roughly five or six months in isolation, he decides to organize a masquerade ball. This is a grand and luxurious event. However, an unusual aspect of it is that the ball is held in seven different rooms. Moreover, what is unique about these rooms is the fact that each room is decorated in a different color: blue, purple, green, orange, white, violet, and black.