Super Mario Bros.
The fourth level is a castle. Mario faces lava, fire bars, and other enemies in this level. At the end of the level is Bowser, who stands over a lava pit. Mario can throw fireballs to defeat Bowser. He can also jump over or run under Bowser to an axe. Touching the axe will destroy the bridge and cause Bowser to fall into the lava, defeating him. Toadstool's servant, Toad, will then tell Mario that the princess is in another castle. The eighth boss is the real Bowser and instead of Toad, the princess is there.