Bowser's Castle
Bowser's Keep (also known as Bowser's Castle in some games or Castle Koopa in the Mario TV series) is King Bowser's home and the base of operations for the Koopa Troop, and is always the final area Mario visits to rescue Princess Peach. It is guarded by Koopatrols, Magikoopas and Hammer Bros.
Shown in Super Mario Bros. 3 and Paper Mario: The Thousand-Year Door, it is found in the Dark Land, whereas in Super Mario World, Bowser's Keep is found in the Valley of Bowser.
In the Mario Kart series, there's a course in each game that takes place within Bowser's Castle.
During the events of Super Mario RPG: Legend of the Seven Stars, Bowser’s Keep is isolated on a mountain of red, jagged rocks. The keep rests on the largest rock, which, in fact, resembles Bowser himself. The castle can only be accessed by a long bridge that connects to the faraway Vista Hill. The halls of Bowser’s Keep are lined with statues of Hammer Brothers and Bowser. The castle is originally guarded by Terrapin soldiers. Additionally, molten lava flows through the keep in several areas. Fortunately, several bridges allow access across the lava (Unfortunately, the bridges are wooden, and as such, will eventually collapse in a room filled with lava. In fact, one bridge breaks right after Mario walks across it. Later, this bridge is replaced with hovering Donut Blocks.) The castle is also filled with ornate chandeliers. Mario and Bowser actually duel on the top of these chandeliers.
Bowser’s Keep was also the Smithy Gang’s base of operations in the Mushroom World. During the beginning of Smithy’s invasion, the gigantic sword Exor crashed into the keep. Since Exor is the gateway to Smithy’s dimension, the soldiers of the Smithy Gang had an easy time taking control of the castle. In fact, many of Bowser’s soldiers defected or ran away instead of fighting. Eventually, the Smithy Gang claims the castle as their own. Additionally, Exor destroyed the bridge connecting Bowser’s Keep to the outside world. As such, the castle can only be accessed by flying vehicles.
In Paper Mario, Bowser and Kammy Koopa use this castle to steal Peach's castle, and lift both into the stratosphere after imprisoning the Seven Star Spirits and stealing the Star Rod. But Mario, with the help from party members Goombario, Kooper, Bombette, Parakarry, Lady Bow, Watt, Sushie and Lakilester, manage to take back the Star Rod and save Princess Peach.
In Mario & Luigi: Superstar Saga, Bowletta used Bowser's Castle to attack the Beanbean Kingdom. This castle could fly and looked like a statue of Bowser. It ended being blown up.
In Mario & Luigi: Partners in Time, the four heroes get to see a little of Baby Bowser's castle.
Only a hallway of the castle is seen in Paper Mario: The Thousand Year Door.
