In an era where talented finish carpenters whose skills were at furniture maker levels could be found by putting a sign out at the street, details like this graceful curving stair railing and the built-in seat under the windows on the landing were expected by home buyers. Such details were custom made at the site, as were most of the windows and built-in elements.  Sadly, the era of the hand-built, custom made house has vanished except for the very rich.