Kenlun

This elven structure stands isolated in the middle of the forest, with a paving stone path leading from the front courtyard and trailing off into the greenery a quarter of a mile away. Though it is constructed entirely via elven stone- and wood-shaping, its architecture is an odd blend of human and elven, with the classical elven flowing lines that form a building in the form of a human mansion.
The garden in back is incredibly overgrown, and the paving stones in the front courtyard have been broken apart and a sparse forest of saplings has begun to grow out of the cracks. Most of the structure’s roof has fallen in, but the walls are mostly intact. One part of the building was apparently constructed out of a living tree, and though it has been untended since the building’s abandonment it has continued to grow, and has broken away from the surrounding stone walls. Now, the tree’s exterior is a distorted spiral staircase, leading up into a ramshackle treehouse twenty feet above the forest floor.
Gremlins have taken up residence in the chateau, and have proceeded to tear the place even further apart. Walls have been defaced with graffiti smeared on in blood and feces, anything that can be broken by tiny humanoids has been, and the only reason that the walls are still standing is because the gremlin’s boss, a Winter satyr named Alia Spitehoof , has ordered them to leave the structure’s bones intact.
Worse than the gremlins, though, is the fact that Spitehoof has ordered the kidnapping and enslavement of fey from the nearby forest. She keeps them under control via the Warden's Pipes she carries, which allow her to restrain them with illusory cold iron shackles. Her plan seems to revolve around infusing as many forest fey with Winter magic, converting them and eventually the forest to the Winter Court.

Update:

With Velena's help, the party slew the Spitehoof and her gremlins, freed their slaves, retrieved the Contemplative, and sold off the Warden's Pipes. The chateau is now under renovation, having been granted by the Green Man to Fariday as a reward for his services to the Court of the Green.
After a bit of divination magic, the structure’s original name was revealed to be “Kenlun” - likely a derivation of an olde elvish phrase meaning “Guest’s Home”

Related Report (Secondary Locations)

• The Hodag & Velena