It takes a special grade of Back Bay townhouse to make us pause—there's just so many banisters and balustrades one can absorb before they all start running together. But the manse at 410 Beacon Street does cause us to slow a bit. It's got the typical assortment of space and luxury: 4 bedrooms, 7 bathrooms (5 full), 9,107 square feet, a library, a media room, and an elevator that goes to all six floors. It's got the suitably if-you-have-to-ask-you-can't-afford-it tag of $9,650,000. Then you dig deeper and you see the ample closet space throughout (there appear by the floorplans to be at least six walk-ins); the two top decks, back and front; the bedroom on the fourth floor outfitted to be a gym; the main hall's exposure through the second floor; and the renovation that brought its late 19th-century style up to early 21st-century convenience standards. Plus, there're the views. Riverside, baby, riverside.