Chidlaw Building, Military office building in Colorado Springs, United States.

The Chidlaw Building is a multi-story office building on East Bijou Street in Colorado Springs, Colorado, originally built for military operations. It has underground levels and was constructed with reinforced walls and specialized technical systems to support its intended use.

The Chidlaw Building was built in 1963 at 2221 East Bijou Street as headquarters for the Aerospace Defense Command and NORAD, consolidating Air Defense Command personnel from 14 locations, including Ent Air Force Base. Its Combined Operations Center, transferred from the Ent AFB combat center, held an IBM 1410 computer by 1965 and served as the primary node of NORAD's Alert Network Number 1. Renovated into an office building in 1993, it lost its main tenant PGi in 2011 and went into foreclosure in 2012.

The building is named after General Benjamin Chidlaw, who led North American air defense in the early Cold War years. Today the building has shifted from military to civilian use, though its heavy construction still reflects its original purpose.

The building sits on East Bijou Street in Colorado Springs and is easy to reach by car, with parking available nearby. Access to the interior may be limited, so the exterior is best viewed from the street.

The building's Combined Operations Center was the primary node of NORAD's Alert Network Number 1, the highest echelon of command and control for the SAGE air defense system. It received divisional air defense status from AN/FSQ-8 Combat Control Centrals at SAGE combat centers, and an IBM 1410 computer was installed there in 1965 for systems analysis.