Insurer acquires 330 Stuart St. for \$28m Liberty Mutual Group, the second-largest international insurer based in the United States, bought an office and retail building across the street from its headquarters in Boston for about \$28 million. The building, at 330 Stuart St., has 105,000 square feet of space, Liberty Mutual said. The seller was the Massachusetts Higher Education Assistance Corp. Liberty Mutual plans to renovate the ...