At the very edge of the school grounds stands the legendary Thirteenth Tower. Why, exactly, it's called the Thirteenth Tower is a mystery, for Ilvermorny's ground do not, in fact, possess enough towers to add up to thirteen, even if the distant no-maj memorial tower is counted.
At first glance, most would say the tower is older than the school itself; dilapidated and in extreme disrepair, the Thirteenth Tower is mostly surrounded by the woods that have grown over the slopes of Mount Greylock since before the school was even a glimpse of an idea in Isolt's mind centuries ago. Before the crumbling ruins in a sizable clearing over which the tower looms like a dark spectre. To even stand before it causes unease in all but the bravest and few ever venture within.
Of course, that feeling has given rise to the school myth that the tower is haunted. No one's ever proven it one way or another but that doesn't stop the story from being perpetuated by the older kids to scare the new blood..,