Madison Avenue’s Rhinelander Mansion has long been the grand dame of Ralph Lauren’s ever-expanding retail family. Now the company has unveiled quite the companion—a 22,000-square-foot neoclassical mansion, built from scratch over the last two years and located directly across the street (888 Madison Ave., at 72nd St.; 212-606-2100). With the original manse now devoted to menswear, the new store—designed by Lauren favorites Weddle Gilmore Architects—will spread the label’s women’s collection, fine jewelry, and housewares over four floors, all joined by a luxuriously winding limestone staircase.