WASHINGTON — You may think you know all about the secret government facilities in our area. But how well do you know Mt. Weather?

It’s on the edge of Loudoun County, Virginia about 50 miles from the District, and serves as the backup site for the national emergency operations center run by the Department of Homeland Security. That’s what NBC Washington discovered after a power outage in April.

NBC4’s Scott Macfarlane reports the center has been a FEMA site since 1979. Before then, it was prepped as a possible relocation site for government bosses during the Cold War. It was built as a weather station all the way back in 1902.

In a statement, a Homeland Security spokesman confirmed to NBC Washington that Mt. Weather was activated during the outage in April:

“Continuity of operations is critical in ensuring that the Department of Homeland Security’s (DHS) missions continue to be performed during a wide range of emergencies such as natural disasters or power outages,” the spokesman said. “During the power outage impacting the National Capitol Region on April 7, the DHS National Operations Center (NOC) shifted operations to an alternate site out of an abundance of caution to ensure uninterrupted operations.”

Watch NBC Washington’s report: