Heroes of the Borderlands, Page 15

15.  After that, determine who legally owns the land the Caves of Chaos is under.  If these Caves are owned by the Keep, then have the PCs ask the Castellan of the Keep to purchase the Caves of Chaos.  Give an option for the players’ party to use these caves and the land over these caves as their Bastions.  Owning this land will give the players rights to harvest timber and animals on the land - as well as excavating any resources under the ground.