The 5,528-square-foot Colonial-style townhouse at 13 Louisburg Square sits in "one of the most prestigious of neighborhoods in the country," as its Brewster & Berkowitz listing so aptly puts it. It's not just Beacon Hill—it's Louisburg Square, home to some of the most ornate and stylish properties in the Boston region, including No. 19, the long-time residence of Secretary of State John Kerry and wife Terese Heinz Kerry. The 12-room, five-fireplace No. 13 just hit the sales market and has not traded since December 1990, when it went for $1,150,000. It wants slightly more than that this go-round.