From the Pittsburgh Post Gazette:
Iron Mountain can show off plenty of these rooms across more than 200 acres of underground space carved into an abandoned limestone mine in Butler County. The facility — famous for its geology and for holding some of the most precious pieces of paper and film in America — lately has been installing large racks of blinking computer servers that stretch as far as the eye can see.
The Boston-based information management company that owns the mine has been advancing deeper into the shafts to serve health care and insurance businesses, financial institutions and tech companies looking for the safest place to store their irreplaceable digital information.
The mine contains more than 230 private vaults, many of them managed by government agencies like the National Archives and Records Administration, U.S. Patent and Trademark Office and the Social Security Administration.
The mine also houses treasured film records from virtually every major motion picture company in the country, said Troy Hill, senior manager of data center infrastructure for Iron Mountain.
From 2014: Video Tour (via Iron Mountain)
From 2014: KDKA Television Segment