Just where is the mirror room?

Start at the entrance to the castle. Go up the stairs infront of you and into the center door (right in front of you too). Run up the stairs. In the next room, take a right and go through that door. Enjoy!

It's on the 2nd floor.

Hey lordck1992 it took me a long to figure where it was, actually my uncle found it. You know where the main part of the castle is? Where the star door is that you have to have 12 stars to unlock it. To make it more exact where the bob-omb battle field and cool cool mountain levels are. Well walk up the big stair case in the middle and go through the doors right in front of you. Know I'm going to tell you were to find the key for the doors. First go through 1 of the wooden doors that's in the main part of the castle.then insted of following that boo that is always over there go down the stairs that lead to the basement. In order to get the key for those doors you have to beat the star door in the main part of the castle, when you beat bowser in that level he'll give you a key that has horns on it. Take it to the doors and unlock them. Now when you go through those dorrs if you look to your left there will be another star door. It takes 30 stars to open. When you have it open jump through that twirly water wall type thing beat that level then once you've beat it there should be more room to walk forward. There should be a squared whole on top of a little hill. Go through that and beat bowser in that level he'll give you another key with horns. I know what your thinking, that key is not going to work because it looks just the same as the one that he gives you when you beat the star door in the main part of the castle. Don't worry it will work. Take it to the doors in the main part of the castle. You know the ones up the big stair case I mentioned in the beggining. Then unlock the doors and then go up the set of curved stairs open the door and VIOLA it's the moment you've been waiting for, the mirror room. There should be a nother set of curved stairs if you walk to the right. But when you fist come through the door there should be a big picture of a water spider in the middle. And a picture of little yellow stars and a blue background on the left and right of the spider picture. I don't know if that big room is the mirror room but the mirror room is in that big room. If your still by the door in the begining of that room. Then walk to your right you should see a door withe a star in it by a picture of bob-omb walking. Go through it then there is the actual mirror room. When you walk up the little set of stairs that whole back wall should be a mirror. To your right you should see a picture of luigi 2 goombas. There should also be 5 posts 2 of them should have power flowers get one if your luigi then you should be able to walk through the mirror. So walk through the mirror look to your right and there should be a picture of wario jump in it and defete chief chilly's challenge. Warning! When you get to face him watch out it is slippery. When you beat he should give you a key with wario's cap on it, get it save the game if you want to, take it to wario's door unlock it and there you have it wario is unlocked. I hope I helped out... Alot. That reminds I am so sorry that this is alot to read.really really sorry. Oh yeah, sorry I didn't tell you that you had to be luigi to walk through the mirror before. Hope you had a fun time doing all that.p.s. Feel free to ask more questions about the game if you need to. Well, piece out!