During Season 1, Derek Hale lives in the ruins of Hale House. It is where he attempts to train Scott McCall to control his werewolf nature. During Formality and Code Breaker, Derek was locked up and tortured under the house. The final battle of the season is fought here as well.
In Season 2, Derek comes back to the house looking for answers to the Kanima. It is also where The Alpha Pack leaves their symbol to show Derek, Issac and Peter that they were in Beacon Hills.
In the Season 3 premiere, Tattoo, it is revealed that the county now owns, "has taken control of", the property and the House.