I only know of two instances where you need to get in there. One is if you have a school assignment for fire wizard. The second is for any wizard class and it is a quest from T'in Bhu (?) outside the spiral gate in Krokotopia. He wants a fire gem which you get from Dhalia Flamea. She doesn't have one so she sends you to the ring shop and he tells you to get one out of the Dragon Cave.