Built for textile tycoon Walter C. Baylies, 5 Commonwealth Avenue is the second house to occupy this site, replacing what had been a twin to the French Academic–style 3 Commonwealth, next door. Set behind a high iron fence punctuated by tall urn-topped piers, its limestone facade is discreetly ornamented with molded window surrounds, piano nobile balustrades, and attic swag panels. To the left of the main block, below a bulbous copper roof, is an enchanting single-story wing, added in 1912. Built for the debut of the Baylies's daughter, most of its interior is taken up by a small but exquisitely detailed Louis XVI ballroom.