Curbed is on a roll today, unveiling some floor plan porn for the $24 million maisonette at McKim Mead & White’s 998 Fifth.  The venerable building made a cameo in Rogues’ Gallery because, in a previously unreported attempt at expansion, the trustees of the Metropolitan Museum of Art briefly considered buying  it for its administrative and research offices, some specialized collections and the museum’s  library. Its builder-owner, James T. Lee (grandfather of Jacqueline Bouvier Kennedy and developer of 740 Park), was in deep financial trouble and offered 998 to the Met at the bargain price of $900,000. The museum board’s executive committee, always thinking about the tender sensibilities of its wealthy patrons, finally decided not to evict the seventeen families renting there, some of them contributors, in order to take it over.