North Attleboro, MA Bret O’Brien and James Keefe of Greater Boston Commercial Properties, Inc. represented the seller in the sale of 49 Plain St., a multi-tenant investment property. The 12,222 s/f office building sold for $1.25 million. The price was based upon a capitalization rate of 8%. The sale included two relatively short-term leases comprising 100% of this three-story office building.