The owner of the Charles Hotel in Cambridge’s Harvard Square has purchased an adjacent property where it plans to develop a 65,000-square-foot office building. An affiliate of Carpenter & Co. purchased 114-116 Mt. Auburn St. for $4 million from the Bulfinch Cos. of Newton.

The president of the company, Richard Friedman, said he intends to construct a seven-story office building on the site, which formerly housed a Chili’s restaurant and is now vacant.

The project will include a restoration of the historic MBTA­ Conductors Building on the same block. The building’s facade will be restored, and the interior will be renovated into a restaurant and bar.

Elkus Manfredi Architects of Boston will serve as architect for the project.