Hyrule Castle
Hyrule Castle is the home of the royal family of Hyrule, a mythical land in the popular Nintendo video game series The Legend of Zelda. The castle's first appearance was in the game A Link to the Past, the third in the series. Each game that contains a Hyrule Castle either features a different layout, or denies you access to parts that are available in other games. There are grounds for speculation that the castle may actually be a different castle in each game, or that it is in fact supposed to be the same castle, and it was changed in each game for aesthetic or gameplay purposes.
Various Locations and Descriptions (By Game)
Though there is no actual "Hyrule Castle" in this game, it's equivalent is generally thought to be the Northern Palace, the resting place of Princess Zelda. This is partly because it's the only "friendly" palace in the in game and, like most Hyrule Castles in other games, is surrounded by a moat.
The first official appearance of Hyrule Castle. In this game, it's situated in the middle of Hyrule and is surrounded by a moat. The castle is heavily gaurded, so Link must enter via a secret passage on the eastern side of the castle. The castle features several hallways and various rooms. The castle also features a court yard. In the Dark World, Hyrule Castle becomes the Pyramid of Power.
Hyrule Castle is situated east of Death Mountain and just directly north of Hyrule Castle Town. The entrance to Hyrule Castle Town alone is protected by a moat and a drawbridge which lowers only during the day. Beyond Hyrule Castle Town is a path which leads eventually to Hyrule Castle, but features a gate and several gaurds along the way. In order to infiltrate the castle, Link must sneak past each gaurd until he gets to the castle itself, surrounded by a moat. Link never directly enters any "important" parts of the castle, but he does manage to enter the courtyard (where he mets Zelda) using a secret entrance on the east side (sound familiar?). In the future, Hyrule Castle is destroyed, and replaced by Ganon's Castle.
Hyrule Castle lays just south of Death Mountain, somewhat near the center of Hyrule (seemingly a combination of its locations in A Link to the Past and Ocarina of Time). The interior is very similar to that of the castle's interior in A Link to the Past, while the exterior is similar to The Wind Waker's.
Hyrule Castle, at first frozen in time, is situated under the Great Sea and accessible at the site of the Tower of the Gods. Only the main hall, which contains a passage to a room where the Master Sword is found, and a small courtyard may be visited.
Super Smash Bros. series
Hyrule Castle also appears as an arena in Super Smash Bros., but not in the sequel, Super Smash Bros. Melee, where it was replaced by Hyrule Temple. Super Smash Bros.' Hyrule Castle appears to be based largely on the one present in Ocarina of Time, whereas Hyrule Temple in SSB Melee is seemingly a combination of various Zelda temples and castles.