Fortress

Fortresses, or Forts, are fortified buildings that appear in many Mario games, starting with Super Mario Bros.. Usually, Fortresses are found at the end of levels, behind Goal Poles. After reaching the Fortress, Mario or Luigi can advance to the next level. However, some fortresses, like the ones from Super Mario Bros. 3 and Super Mario World, are more like castles.

In Super Mario Bros., Castles appear to be a fortress stacked upon a larger section.

In Super Mario Bros. 3, the fortresses that advance Mario to the next level do not appear. Instead, Fortresses are usually found in the middle of worlds. They are levels with Boom Boom as their only boss, and he must be defeated to gain access to other parts of the world.

In Super Mario World, Fortresses are guarded by Reznors, but are far less common, as there are only four in the game, and only one of them is mid-world. Fortresses are normally inaccessible after being completed, unless the player presses while holding  and  when at it on the map.

Forts also appear in the Yoshi series as the mini-boss levels of each world.

The End-of-Level Fortresses later return in New Super Mario Bros., New Super Mario Bros. Wii, New Super Mario Bros. 2, and New Super Mario Bros. U and reprise their earlier role from the first Super Mario Bros. game, allowing Mario, Luigi, and/or the Toads to continue to the next level. Black fortresses appear as parts of secret exits, except in the original New Super Mario Bros. Their mid-world role in Super Mario Bros. 3 is replaced by the Towers.

The Towers in New Super Mario Bros. Wii are called Fortresses in the Prima Games guide.

In Super Mario Galaxy 2, the Bowser Jr. levels at the end of Worlds 1, 3, and 5 are represented in the map as Fortresses. However, only the first world's last level includes a fortress within it.

In Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS, a classic Super Mario Bros.-style fortress appears in the Mushroomy Kingdom stage, in the same place as in World 1-1 of Super Mario Bros.; however, it's in the background, so fighters cannot enter it. It also appears in the latter game's Final Destination version of the stage. Like the rest of the stage, it has a more realistic and withered appearance.

Appearances in other media
In the Mario Ice Capades, during the whole show, King Koopa rode a moving fortress. A fortress also appeared in the background of the show as a prop. In The Super Mario Bros. Super Show!, a fortress appears only in the intro.