Brief Reopening
During the Season 7 episode, "The Killer in Me", Buffy and Spike break into the Initiative to find medicine to dampen the slowly fatal effect of his degenerating chip. While in the abandoned complex, they are attacked by a demon who has managed to survive for over three years. After defeating the demon, they run across operatives sent by Riley Finn who remove Spike's chip.
In the penultimate episode of Season 4, the government overseers rule that the former Initiative base would be filled with cement to hide evidence of its existence, but in "The Killer in Me", Buffy and Spike are able to access the ruined facility.
Read more about this topic: Initiative (Buffy The Vampire Slayer)