Nope, a Stronghold is pretty different. A normal underground area (I just call it a dungeon) is simply pathways through the ground that lead deep beneath the surface. Sometimes it'll be chasms or mines as well, but usually it's just areas that cut through the ground naturally.

A stronghold is a rather special thing. There are only three of them in every PC world, despite being absolutely massive, which makes them incredibly rare. They're typically found by throwing an Eye of Ender into the air and lookiing at the direction it falls. That is your homing detector for where your nearest Stronghold is. You can always tell when you're in a stronghold because the brickwork changes. It goes from normal looking stone to blocks that actually looks like brick. Strongholds are typically very large (at least in the PC version) and sometimes also include an End Portal, which is your gateway to getting into The End, the third world besides the Overworld and Nether.

Check it out here: http://www.minecraftwiki.net/wiki/Stronghold

Ahh, yeah, the Witch Houses are pretty crazy. They are not easy to deal with, those guys. I'm not sure about the spawn rates though. It was a long while back that they made it so the animals don't respawn, but that's about all I know of, but I believe there was mention somewhere that the animals would mostly appear in specific habitats and what not, so you definitely have to travel for some.

They do quite well with the lighting and ambiance though, definitely. I really love Minecraft. It's a really great, unique game.

I died about 10 minutes into my first game. Apparently no one decided to tell me not to touch the creepers. Currently I am in my second game, and I have only played that game for about 2 hours and I haven't played it in many months.

And here's the build you wanted to see, though this is for anyone who wants to look at it. *chuckles* I got a little inspired after seeing so many castles in Skyrim and, since everyone likes a castle, I figured why not?

http://imgur.com/K5AmMVj

Amusingly, this was a bit of a speed build. I started this at around noon my time (so about seven hours ago), cut down the side of the mountain, hollowed out the one area and then started building with all of the cobblestone I got out of the mountain itself. Built the keep in the back, then the towers, grabbed some sand to make the sandstone bridge and cut out the ground for the moat.

There are more pictures if you want to see.

You finished that entire castle in a few hours? 0_o

That's amazing lol. It would probably take me 2-4 weeks to make that (and that's with playing a decent amount every week).

Send that pictures! That's a pretty cool castle.

About seven hours start to finish, all in all. I was inspired and worked my butt off to get it all done. *chuckles* And thanks! Appreciate it.

I'll see about the best way to get all the pictures online in an Imgur Album or something in the next while!

And here's the pictures!

First screenshot, 12:18, but I'd probably been working things for about twenty minutes before that.

Last screenshots, around 6:50 pm.

Here's the album of the screenshots I took during the construction! Enjoy!

http://imgur.com/a/tssf9#0

Nice, that's skilled! 

I finally finished the steps up the side of my castle. It's not a great view of it but gives you an idea of what's going on.

Thanks! I'm pretty happy with the castle. I need to do some modifications still and I need to figure out how the hell to get the obsidian I need for a Nether portal...and then to figure out the best way to connect it to my network. My central home is a good distance away. I'm considering new builds as well, so I'll definitely see about keeping ya apprised about that. heh Want to see the underwater rail tunnel I built a while back?

And nice steps! Those are the types of blocks that are usually available in strongholds. They're quite nice! Can't wait to see what your castle looks like when you get it done. heh I see what you mean now about the irritation of the height limit though. That would have to be frustrating. If you want to artificially increase that in future builds? Consider digging down into the ground and remaking the landscape to what you want it to look like, but ten or twenty squares lower. It'd be a hell of a build, but it could still work...

Man though, wish there was a good way to open my PC world for folks to look at. Lots of stuff to see.

If you want obsidian you can just take a bucket of water and pour it over a lava pool and it will turn to obsidian (I have enough obsidian in my mines right now to build an obsidian castle lol). 

I've already taken down the mountain I'm on by about 10 blocks (which equaled 15k dirt and 5k stone) so it should be enough for a decent looking castle. I decided to use the brick stone because I figured it would look the best for a castle on top of a mountain.

Can't the PC version have friends join in your game?

And yes I would like to see an underwater rail tunnel lol.