First shown in 6.02 Two and a Half Men, this appears to be a secure base of operations for the Campbell family. It is located in Lansing, Michigan, and is surrounded by a chain link fence with a gate across the road. The fence and gate are topped with barbed wire. The main building has corrugated metal walls and is full of a variety of weapons and supplies. It also contains a small kitchen area and various furniture, such as tables, chairs, and shelves. Underneath the compound building is an unfurnished panic room with steel walls and a devil's trap on the floor. Also under the compound building is the Campbell family library, accessed by a hidden trapdoor in Samuel's study.
Campbell Family Library
The Campbell family library is visited in 6.18 Frontierland when Sam, Dean, and Bobby are searching for a way to kill Eve. Sam seems to remember its location, hidden underneath Samuel's desk, from memories of his time without a soul. It is likely that Samuel collected the components of the library himself. In addition to shelves of books, a filing cabinet, desks, chairs, and a lamp, there is a wall of old portraits, possibly of the Campbell family. Its contents are presumably taken by Dean, Sam and Bobby as Bobby has at least one of the Campbell family journals in 6.21 Let It Bleed.
Samuel's Grandfather's Journal
This book is first shown in 6.05 Live Free or Twihard, but Samuel had told Sam about its contents during the year Dean spent with Lisa after the Apocalypse. Samuel retrieves the book to get the recipe for the cure for vampirism.
Samuel Colt's Journal from 1860
Sam, Dean, and Bobby search through many other books in the library in 6.18 Frontierland, including one that appears to contain a resurrection spell. Bobby also finds a book that says the ashes of a phoenix can wound Eve.
While on the run with a baby shapeshifter, Sam persuades Dean that they need the help of the Campbells in deciding what to do. The brothers drive to the compound and are allowed through the gate by guards. Later, when the Alpha Shapeshifter attacks, they retreat with the baby to the compound's panic room. However, the shapeshifter is undeterred, and rips out the door of the room to take the baby.
On the phone with Sam, Dean says that he will be at the "Campbell base" in ten hours, but Sam redirects him to Easter, Pennsylvania.
After determining that Sam has been resurrected without his soul, the Winchesters go to the Campbell Compound to speak with Samuel. When they enter the main building, they see a number of people engaged in preparations for hunting. They go to Samuel's office, where Castiel appears and reads Samuel's soul, determining that it is intact. The Winchesters remain at the compound to join an upcoming Campbell raid on the Alpha Vampire and to spy on their grandfather. Dean attempts to break into Samuel's locked office with his lock picks, but is interrupted by Christian Campbell before he can search it. Later, after Samuel captures the Alpha, he hides it in a warehouse location separate from the compound. Sam and Dean follow him from the compound to this satellite holding area using his cellphone's GPS.
Sam, Dean, and Castiel break into Samuel's office at the compound to search for information on Crowley's activities and location. Samuel catches them.
Sam, Dean and Bobby are researching ways to defeat Eve, and Sam leads them to the Campbell family library. A trap door under the desk in Samuel's office leads them into a small room walled with bookshelves. They study the volumes at a table in the center of the room. Dean finds Samuel Colt's journal. The compound appears abandoned following the death of Samuel.