There’s a lot to love about the aristocratic brownstone mansion at 231 Madison Avenue, at the southeast corner of 37th Street.
Built as one of three freestanding mansions between 1852-1853 by members of the copper-baron Phelps family just as Murray Hill was transitioning from countryside to a posh urban neighborhood, the house was enlarged in the 1880s—then purchased by J.P. Morgan in 1904 as a 45-room family home for his son and business partner, Jack.

A study in harmony and symmetry, the mansion possesses the kind of elegant restraint of many Murray Hill townhouses. But one decorative element delights me every time I walk by: the wrought-iron balustrades on each of the full-length front windows flanking the entrance.
A collection of vines, florals, and curlicues, each balustrade adds a little Art Nouveau-inspired whimsy to the block, home to the Morgan Library & Museum. (J.P. Morgan’s own mansion was on the northeast corner, bulldozed in 1928. Today, number 231 is owned by the museum.)
Unsurprisingly, the balustrades were not part of the original antebellum mansion when early Phelps family members made it their home. They’re a product of either the 1888 renovation, or the “modest” exterior work Morgan commissioned shortly after buying the house, according to the Landmarks Preservation Commission’s (LPC) 2002 historic designation report.
The LPC report notes that 231 Madison Avenue “was a house that harmonized with the home of the elder Morgans and evoked comfortable prosperity rather than wealthy ostentation.” The balustrades also match the wrought-iron fence, as seen below.
The window railings are as beautiful as the one on the front window of the William and Clara Baumgarten House, a Beaux-Arts row house on Riverside Drive and 101st Street. Berenice Abbott captured a 1937 image of the windows while photographing the stoop—as lovely now as they appear then!