The architects of a number of striking projects featured in this month’s RECORD have radically reimagined new spaces within existing structures. A brick university laboratory in Amsterdam has been re-fitted as a hipster hostelry. An old gymnasium in London—think 19th-century health club—has been transformed into a dramatic high-end restaurant. A 1930s hospital on an island in the Venice lagoon has become a sumptuous luxury hotel (you can’t beat the location). These projects are all part of a contemporary trend to adapt everything from bank buildings to factories into dynamic hospitality spaces.

Yet the more distinctive the original architecture, the more challenging that adaptation can be. Take Eero Saarinen’s spectacular TWA Flight Center at JFK Airport in New York (1962), a building in search of a purpose ever since it was mothballed in 2001. Now, it appears, work will finally begin to convert the landmark into a hotel, with a renovation and expansion by the firms Beyer Blinder Belle and Lubrano Ciavarra Architects. The concept is to make it the grand entrance, with lounges and bars (there were several originally; to get travelers in the mood for where their awaiting jet would take them, they had names like the Lisbon Lounge and the Paris Café). The new hotel’s developer proposes to construct two six-story structures behind Saarinen’s birdlike icon, to hold 505 guest rooms and 40,000 square feet of meeting venues.

Assuming the renovation of TWA is undertaken with a light touch, this is good news. The interior space is as astonishing as the exterior but rarely has been accessible since it closed. Last month, the nonprofit Storefront for Art and Architecture—an exhibition space and forum that explores experimental ideas across disciplines—managed to commandeer the terminal for its annual gala. To be there, not on an architectural tour but among hundreds of revelers, was to see the space in a spectacular new light. Saarinen knew about theater—and the human comedy—and what he created for the terminal’s interior was a stage set for people on the move. Its curving stairways and bridge-like balcony, its swooping, red-upholstered conversation pit, all of it animated by partygoers and saturated with music, was like being at the opera, the performance and intermission rolled into one. It is a place that deserves to be populated as well as preserved.

While the TWA terminal transformation is hopeful, a more serious change awaits another stunning modern masterpiece. Later this month, the Four Seasons Restaurant, designed by Philip Johnson in Mies van der Rohe’s Seagram Building in New York, will host a fundraiser for DOCOMOMO, the organization dedicated to documenting and protecting buildings of the Modern era. That is both deliberate and ironic because, it turns out, the restaurant’s spaces are not fully protected, despite being “among the finest International Style interiors in the United States,” according to its 1989 landmark designation. While the interiors have remained virtually unchanged since opening in 1959, the landmark status only applies to fixtures that cannot be moved. After a drawn-out drama—involving a new owner of Seagram, who inflicted a huge rent hike on the Four Seasons—the restaurant’s owners are departing for a new location, taking the name and not much else with them. Another restaurant will open in the same Seagram place—but it won’t include the original custom furnishings. Everything that’s not nailed down—from the tables, chairs, and barstools by Mies and Johnson to the beautifully simple flatware, designed by Garth and Ada Louise Huxtable—will be auctioned next month

One of many architects mourning the end of the Four Seasons recalled her father’s first bringing her there when she was 10 years old; and everyone in the design world who loves the place has his or her own memories. There’s still a little time for a last lunch or dinner, or a drink at the elegant four-sided bar, before it closes on July 16. And then, it really will be last call.