Derek's Lair is where Derek Hale lived once he returned to Beacon Hills in Teen Wolf Season 1. He's moved locations three times over the course of the first four seasons.
Derek Hale operated out of his family's burned out home within the Beacon Hills preserve when he first returned to town at the beginning of Season 1.
He was held captive and tortured in the basement of the house and his uncle was ultimately buried under the floorboards.
At the beginning of Season 2, Derek moved into a new lair in the heart of the warehouse district of Beacon Hills, California.
The large, nearly empty, space has concrete and steel walls supported by steel beams. It was apparently in the former Beacon Hills Railroad Depot and is dominated by a large rusting subway train car.
The location of the lair within the city limits of Beacon Hills is shown on a map the Hunters are using in their attempt to track Derek's location.
After the resurrection of Peter Hale, Derek moved back to Hale House. It's unclear if this is because the Hunters were closing in on the lair, or because Lydia had found him at the new lair and he felt the train station was no longer safely hidden.
Sometime during the four months between the end of Season 2 and the beginning of Season 3, Derek moved into a downtown loft apartment.
It is a spacious lair with exposed brickwork and large arched windows.
In Lunar Ellipse, Derek moves out of the loft and travels to South America. He moves back in the loft upon his return.
While Derek had left the loft, The twins use it in More Bad Than Good to meet Scott so they can teach him to release his inner animal now that he is an Alpha.