If Downton Abbey ever has a Boston spinoff, it might be set in this ginormous Back Bay mansion dating from 1867. It stretches across 50 feet of Commonwealth Avenue and basks in some serious natural light (note on the floorplans the front bay windows, the soaring first-floor ceilings and the skylight), with said light bouncing off original details and elaborate woodwork. Its five floors include not only seven marble fireplaces, but the potential for several bedrooms and not a few studies. Indeed, the fourth floor alone, by the looks of the floorplan, offers the chance at 10—10!—bloody bedrooms. (They were probably staff chambers at one point, but your Emerson-educated guests keen on seeming more egalitarian than elitist won't know or at least would never say.) The mansion retails at $15,900,000 through Jeannemarie Conley at R.M. Bradley & Company.
· Listing: 15 Commonwealth Avenue [R.M. Bradley & Company]