The UN Plaza Hotel Ambassador Grill and Lounge, designed by Pritzker Prize–winning architect Kevin Roche and John Dinkeloo and completed in 1975, cleverly uses mirrors and lighting to create faux skylights that help transform the basement space into a theatrical yet tasteful dining room that feels surprisingly spacious. If Mad Men aired for another few seasons, we surely would have seen Don Draper brokering international ad deals in its velvet banquettes. Maybe that would’ve helped cultivate some romantic attachment to the spaces, which are now under threat.

The hotel was renovated and rebranded as One UN New York in 2012 by owners Millennium Hotels and Resorts, who announced the second phase of their renovation last November, promising “the debut of a new restaurant and bar concept.” It was a call to arms for preservationists, who were further alarmed by reports that exploratory demolition was underway in the Ambassador Grill despite a lack of permits. The reports were disputed by Millennium, who closed the restaurant last year and said that no decisions have been made.

Opponents of the presumed renovation are seeking to protect the restaurant, as well as the hotel lobby—a decidedly postmodern hive of reflective glass and marble completed in 1983—by having them designated interior landmarks.  In early January architecture advocacy group Docomomo US filed a Request for Evaluation with the Landmarks Preservation Commission and have created a petition to raise support for an expedited public hearing. To qualify as a landmark, an interior must be 30 years old, publicly accessible, and have a “special character” or historical import that gives it cultural value. Those against landmarking call the spaces ugly and dated; those in favor argue that they are some of the most intact and significant late-modern spaces in the city and an exemplar of Roche’s use of mirrored glass, which he pioneered in 1962 while working on Bell Laboratories for Eero Saarinen.

Of the 117 interior spaces that have earned the landmark designation since it was initiated in 1973, only four are restaurants, including the Four Seasons, which has been threatened despite its status. Currently, the “youngest” interior landmark is Roche and Dinkeloo’s 1967 Ford Foundation, so the actions of the commission are particularly important because they’ll set a precedent for the preservation of late-modern and postmodern architecture in New York.

In lieu of a Draper-esque pitch to inspire careful action moving forward, the comments from the 1982 Pritzker jury seem apt: “In this mercurial age, when our fashions swing overnight from the severe to the ornate, from contempt for the past to nostalgia for imagined times that never were, Kevin Roche’s formidable body of work sometimes intersects fashion, sometimes lags fashion, and more often makes fashion.”