Memory Repository
Located within the Thought Chamber, opposite the Brain Room, in the Department of Mysteries is the Memory Repository. It is here that important memories are donated or harvested. The repository is filled up with shelves of memory strands in containers and several pensieves. Some say it looks like a smaller more watery version of the Hall of Prophecies.
The original memories are heavily guarded and the number of copies is strictly regulated to ensure the original is not degraded through copying. Via special requests copies of memories can be checked out to be used in other pensieves outside of the Ministry.
The most secretive of memories (the kind that required heavy Obliviation after extraction) cannot be accessed except by Memory Repository Unspeakables.
At Absit Omen
Prof. Sissel Jowd has been using his past with the Dept. of Mysteries to request memories from here for use with his pensieve flashback field trips in History of Magic Class.