NEW YORK CITY — Harbor Group International (HGI) has entered into an agreement to buy 51 West 52nd Street, an office building in Midtown Manhattan known as the CBS Building, for $760 million. As the former owner-occupier, ViacomCBS will lease back its space on a short-term basis. The deal marks the first sale of the building since it originally opened in 1964. HGI plans to implement a significant capital program to reposition the property in support of a long-term leasing plan. Updates will include significant upgrades to the lobby and other tenant amenities. CBRE leases the building. The deal is expected to close by the end of the year.