As Boston Properties has grown, it has focused on developing in a select group of markets across the United States, including Boston, New York City, Washington, D.C., and San Francisco. “Those are the best properties really in the United States,” Construction Project Developer Robert Kain says. San Francisco is the location of one of Boston Properties’ most prestigious projects, Salesforce Tower, which is under construction. When completed, the new tower will stand 1,070 feet with 61 fl oors. “It’s going to be the tallest building west of Chicago,” Kain says.