The exacting techniques of proper storage take place in the Collections Building (which is the former bunker used by the Federal Reserve) and the Nitrate Film Storage Building. Both areas are underground and climate controlled, but whereas the bunker that became the Collections Building had to be completely gutted before being reconfigured with high–density, mobile shelving, and reinforced to accommodate the substantial weight of the Library's collections, the Nitrate Film Building was built from scratch and has specially designed blast–proof vaults for storing the unstable nitrate film used for motion pictures before 1953. Both buildings are energy–efficient and well suited for the low–temperature, low–humidity storage, that is so necessary for long–term preservation.