An impressive and historic 50-room home built in 1872, the Ames-Webster Mansion is one of Boston’s biggest properties and when bids wrap in mid-December, is expected to fetch between $18 and $25 million. Designed by Peabody & Stearns and built for industrialist Frederick Ames, the five-story mansion has 26,000 square-feet filled with 28 fireplaces, a carved oak staircase, 18-foot ceilings, a mural designed by French painter Benjamin Constant and a grand stained glass skylight by John LaFarge. The Back Bay home is currently used for office spaces and is wired for a T-1 line and has video surveillance and a swipe-card entry/security system. [via luxist, boston globe]