"The Castle is protected by more than walls you know"

--Hermione Granger on the castles protection

Hogwarts Castle is a magical building with many towers and turrets, built over a thousand years ago by a wizard architect. It is home to Hogwarts School of Witchcraft and Wizardry. If Muggles approach the castle, all they will see is a mouldering ruin with a sign warning them to keep out and that it is unsafe. It is also protected by numerous ancient spells and incantations to protect the inhabitants, strong enough to apparently resist the dispelling effects of the Taboo. Hogwarts is built in a forested area, and sits on the edge of the Black Lake. The castle is located in Scotland, near the village of Hogsmeade. The castle's architecture is always changing, a feature contributed by Hogwarts founder Rowena Ravenclaw.

Below Ground FloorEdit

Chamber of SecretsEdit

"He was standing at the end of a long, dimly lit chamber. Towering stone pillars entwined with more serpents, rose to a ceiling lost in darkness, casting long, black shadows through the odd, greenish gloom that filled the place"
—Harry, exploring the chamber
The Chamber of Secrets was allegedly created deep under the dungeons of Hogwarts Castle during Medieval times by Salazar Slytherin, who disagreed with the other Hogwarts Founders on the merits of blood purity

Harry walking up the chamber

. The Chamber of Secrets was home to an ancient Basilisk, which was intended to be used to purge the school of Muggle-born students. The entrance can be found in Moaning Myrtle's bathroom on the second floor. In order to gain entrance one must say "open" in Parseltongue and a sink will open into a slide. While falling down the large, dark pipe, one can see hundreds of other pipes leading off. At the end of the pipe, one is launched into a damp, stone chamber. This room is stated to be "miles beneath the school".