The Loop’s Rector building was designated as an official Chicago landmark by City Council today.

Built in 1905 at 79 W. Monroe St. by restaurateur Charles E. Rector, the 14-story structure is the oldest surviving commercial high-rise designed by Chicago architect Jarvis Hunt.

Adorned with classical and modernist Prairie School design elements, the building housed several financial institutions in the 1900s, including Bell Savings & Loan Association, which added the iconic “weather bell” sign to the corner in 1951.

The designation will support the building’s $64.2 million rehabilitation by R2 Development LLC as part of the City’s LaSalle revitalization initiative. The project will convert 11 floors of vacant offices into 117 mixed-income residential units and retail space.

The designation protects the building’s exterior elevations, including rooflines.