Preservationists lose sleep when great modern houses go on the market. Many Neutra houses, for example, have been radically altered or even bulldozed after they were sold. Such midcentury dwellings often don’t fit contemporary family life; the Esherick House has only one bedroom and the kitchen, with its sculptural copper details, is “challenging,” says Wright. But that may not matter to the potential buyers who are targeted by these auctions: they treat these houses as works of art. And just in case, the Kaufmann House comes with strings attached, barring its new owner from making structural changes. Christy MacLear, director of Philip Johnson’s Glass House, now a museum, believes art auctions “are a wonderful way to put these modernist homes into the hands of those who will treasure them.” Maybe preservationists can rest a little easier.