Bowser's Castle is a location from the first Paper Mario game (although it is technically also a location in Super Paper Mario), found in Chapter 8: A Star Powered Showdown. It leads to an empty Princess Peach's castle, which leads to the final boss of the game, Bowser. Bowser's Castle contains makeshift shop's and Toad House's made by Bowser's Minions and captured Toads.
Paper Mario: The Thousand-Year Door
Though inaccessible in the game proper, Bowser's Castle is briefly seen at the start of the second paper adventure, where he is informed that the Princess has been captured by someone else. In his rage, Bowser makes it his mission that he must collect the Crystal Stars before Mario does, with Kammy Koopa at his side.
Super Paper Mario
Bowser's Castle is briefly seen at the start of Super Paper Mario, when Bowser and his minions plan on capturing Princess Peach, and are interrupted by Mario and Luigi who come to bust him up for capturing her. However, he is only now planing his atack. Count Bleck appears as an interdimensional hologram and captures Peach, Bowser and Luigi. Bowser gets a new castle later in the game, but it is infiltrated and destroyed by Mario and Co.
Tattles
*It's Bowser's Castle. This appears to be the hangar for Bowser's vehicles.
*Boy! Bowser's Castle. Talk about your basic eerie atmosphere, huh? Oh... I'm nervous and excited at the same time. We're headed for the final fight at last!
*Are we still outside the castle or what? Let's hurry through here. OK, Mario?
*I've gotta hand it to him, Bowser's Castle is amazing! Such creative use of lava flows! It's just like that volcano!
*It's a covered hallway in Bowser's Castle. It doesn't look like anythings amiss in here. Let's press on, Mario.
*Look at the size of that stone Bowser face! He's pretty scary looking. That face gives me the creeps, Mario.
*It's an underground prison cell, Mario. Are you sure you can find the way back to where we were before?
*I wonder where all this lava comes from. Don't you think it's odd?
*Lava, lava, lava! There's such a thing as too much lava, that's for sure. Mario, are you all right in this heat? Boy, it's hot! This adventure has just been one extreme or the other.
*The only way to cross the lava is to have somebody carry us. If we could find a way to cool the lava off, we could probably walk on it, though. And if we have to pass through lava flows, we can have Bow hide us from danger.
*Here's the source of the lava. It's miserably hot when it's flowing. It's not so bad when it's cooled off, though.
*Now we're cooking! I mean, now we're not cooking! It's still hot, but not, you know, burning hot.
*You know, walking on newly hardened lava is not exactly something that your average Goomba gets to experience.
*The lava seems to have hardened as it cooled off.
*There's a treasure chest. Things are looking up. The lava has even cooled.
*It seems to be a cave. Are we below the castle? It's so dark. They must have had problems setting up lights down here. What a pain for us.
*It seems to be a cave. Are we below the castle? It's so dark. How long can this darkness possibly last?
*Ah! We're back inside Bowser's Castle. There's a stone pedestal with Bowser's face carved on it. What poor taste! What an egomaniac! If we push that thing, what do you think will happen?
*It's a hall in Bowser's Castle. I wonder where it leads. We have to hurry! And yet, we should also be careful.
*These stairs aren't lighted very well, are they? I wonder how deep below ground they go. Bowser should really look into some ambient lighting.
*This is a prison cell where Toads are being held. You know... There are Toads here...and beds... It's kind of like a Toad House! Do you think that I'm just an incurable optimist? Well, what's wrong with that?
*Here's the storage room for Bowser's Castle. It looks like one of his subjects is selling his stuff. Ha ha!
*It's a covered hallway. I can sum up the decorating in two words: pure Bowser! Such dark colors and drab lighting! What terrible taste!
*I'm sure Bowser's going to be surprised. I'm sure he'd never believe that we could make it this far. I can't wait to see the expression on his face.
*If Bombette were about three times bigger, we could just blow all these walls up. It would certainly let us move through these areas a lot faster. But that's probably not a good idea. It would be far too dangerous.
*We're somewhere inside Bowser's Castle. This hall is quite large. It also looks quite fortified. I wonder if there's anything good around here? An attack item, maybe?
*Look at all these carvings of Bowser's ugly mug. It's really shameless! I guess he thinks he's cool. Hey, incidentally, about those stone pedestals... Some move and some don't, so check 'em all out.
*Whoa! This corridor has much lower ceilings, huh? I guess I had gotten used to really high ceilings.
*In case you don't know by now, some of these Bowser pedestals can be pushed and others can't. In many cases, you can push them from either the right or left side. I wonder where I heard that?
*This is a hidden passage. It's a bit dark, huh? That's all right. I can sense that something good's in here.
*Some of these Bowser pedestals can be pushed and others can't. In many cases, you can push them from either the right or left sides. If they move, you can be sure they're covering a hidden passage.
*See! A hidden passage. This one doesn't seem to be hiding anything interesting.
*...Nothing. This room's just a dead end. How worthless. Let's go back to the room where the pedestals are and check 'em out!
*This hidden passage looks promising, doesn't it? It must lead somewhere... You know, I hope we're going in the right direction. I feel kind of disoriented.
*We've certainly seen many kinds of treasure on our adventures, haven't we, Mario? There's one that I would value above all others, though. I would keep it in the safest place I know... Mario, please give me your autograph!!
*Again with the Bowser faces! I'm sick of looking at his ugly mug! Let's find the real Bowser and show him who's boss! And then I can meet Princess Peach!
*It's the outside of Bowser's Castle. Even the outside feels gross and ominous. Maybe he wasn't so bad until he moved here. Living in such a dank place isn't good for the soul.
*How many halls have we been through? I wonder what this one leads to... To Bowser's room? Maybe?
*Know what this reminds me of? A ghost story! This would make the perfect setting for a freaky ghost story! We could have Bow and her friends play the scary parts. Remind me to do that some time back at Toad Town!
*It's a prison cell within Bowser's Castle. A lot of Toads are here. It's a bit strange... Why would Bowser ever need this many prison cells? Do you think there are that many prisoners?
*I think we've already come really far. But we're not at Bowser's room yet. Where could he be? This place is so complicated! That Bowser... I really don't like him!
*"I smell treasure!" Isn't that a good Kolorado imitation? Mario? Wasn't that right on? I wonder what Kolorado's doing?
*It's a covered hallway in Bowser's Castle. There's no place to hide around here, that's for sure. Not that we need one, Mario! Who'd hide? Not me!
*Do you think those windows open to outside or to the inner part of the castle? I'm getting totally turned around in here. This castle really is huge.
*It's a room without a window. It also has a chandelier with no lights in it. I'm getting the feeling that Bowser is really going for the dark, gothic look in here. Maybe he hates bright lights.
*All the torches hanging over there... Doesn't their pattern strike you as sort of suspicious? It's almost as if there's a hidden meaning there. What do you say we try to remember it?
*I think we keep passing through the same room. Do you think, perhaps, that somebody's messing with us? Well, it's a waste of time to just keep running around with no clue about what we're doing. It's kind of like what happened in Forever Forest. Say...those torches might hold a clue for us.
*This is a corridor of sorts. I guess it's more like an elevated skyway, though. If a guy were afraid of heights, his legs would probably tremble and he'd probably freak out. Gulp!
*You know, if I were designing a castle, I wouldn't put in so many corridors. Well, whatever. You can't expect Bowser to have good taste.
*This room is one big ego massage for Bowser. I wish we could crush all these statues to dust.
*Stairs again! Do you think Princess Peach's Castle is at the top of 'em? We're almost there, Mario! I can feel it! Onward! The princess awaits!