The Campbell Compound was the gathering place of all members of the Campbell family, and its long line of hunters. This place was first seen in Season 6's Two and a Half Men. During Sam's Soulless period, this is where he stayed along with his grandfather Samuel Campbell, who was the head of the family. It appears abandoned following Samuel's death.
On the outside it seems to be an old shabby building. Although it has a chain link fence around its perimeter, with bared wire on the top. There is only one road into this place, which goes into the one gate. The gate has to be manually opened by someone. In this case, one of the hunters outside. The building also appears to be somewhere in the country side.