At least some content in this article is derived from information featured in Fantastic Beasts and Where to Find Them (film). As such, spoilers will be present within the article.
This castle houses Ilvermorny School of Witchcraft and Wizardry. It stands at the highest peak of Mount Greylock, where it is concealed from non-magic gaze by a variety of powerful enchantments, which sometimes manifest in a wreath of misty cloud.
The castle was once a granite stone house constructed by Isolt Sayre and James Steward to be their home. When it eventually became a school, the cottage kept expanding until it became a castle.