There is 1 Stronghold per world in the Xbox 360 Edition. They can be found using an Eye of Ender. Strongholds are located underground approx. between 20-40. Strongholds are made of varieties of stone bricks, Silverfish stone, oak wood planks, and some cobblestone. They are multi-leveled complexes containing dozens of rooms.
There are several room types unique to Strongholds. There can be 1-3 libraries containing many bookshelves. They typically feature cobwebs, a chest with books and paper, chandelier, and a ladder that leads up to a catwalk lined with more bookshelves. The chest in the library contains paper related material, sometimes even a map. Many rooms are separated by wooden doors or iron doors with buttons. Prison cells are also common. The most important feature of the stronghold is the End Portal.
The room containing the End Portal sports barred "windows", a lava pit, and a SilverfishMob Spawner. The End Portal itself is raised above the lava pit and takes up most of the room.