Ganon's Castle

In Ocarina of Time, Adult Link finds that Hyrule Castle has been transformed into a hideous black fortress used by Ganondorf. Its molten moat can't be crossed until all the Temples are completed so the Sages can build a bridge to the castle's entrance.

Inside are barriers that must be lowered by completing each room linked to them. Link must get the Golden Gauntlets from the Shadow Room to complete the Fire Room and also to reveal the door to the Light Room.

(The Golden Gauntlets can be used outside to lift a stone blocking a Great Fairy's Fountain. She halves the amount of damage you take.)

Once all barriers are down, Link can access the inner chambers, destroying monsters and getting the Boss Key to open the passage leading to Ganondorf and his chance to free Zelda.

Tip: Don't worry about restoring your health after defeating the two Iron Knuckles. When Link enters Ganondorf's Tower room (where Zelda is), all of his health is automatically replenished.