Brigg’s Tor is what the mortals call the site of an ancient fortified crossing, a place where the boundaries between feywild and mortal world were thin enough to step across. A castle was constructed on both sides of the crossing to stabilize and defend it. In the mortal world it was named Calenim, in the feywild Nimgalen.
The lord of the castle, Luinalagos, was one of the lesser archfey of the Winter Court and was not known for his love of the mortal races. Calenim, then, was built rather more stout and fortress-like than it’s twin in the feywild, it’s halls little more than bare stone overlooking the rolling hills. Nimgalen was more palace than fortress, it’s six wings containing gardens, galleries, ballrooms, lecture halls, dueling grounds and even a zoo, all arranged around a towering central spire. Though far from the center of court life, it was still a popular destination for eladrin and other fey nobility.
The crossing was not left out when the eladrin retreated from the world at the end of the Third Age and closed off the portals to the feywild. However, the crossing was a natural phenomenon rather than an artificial portal, and it’s closure was.. traumatic. Both fortresses shattered, scattering rubble for miles. In the mortal world that was the extent of the damage, but in the feywild the land reacted violently, turning into a dangerous wildlands full of shifting terrain and vicious wildlife and vegetation. Luinlagos was said to have been killed in the blast along with his assistants.
Today Calenim is little more than a shell of broken walls around the shattered tower at it’s center, whose pieces still hang in the air mid-crumble.