The idea that Rem Koolhaas and his firm, OMA, staunchly advocate preservation might come as a surprise. His large-scale buildings, such as CCTV in Beijing; or the Seattle Central Library attest to a "starchitect" at work, one who pushes for the new and unique, not the old and historic. Koolhaas, not surprisingly, abhors this hackneyed epithet. And now, two of his past lectures-assembled with a concluding essay by Jorge Otero-Pailos, associate professor of historic preservation at Columbia University-make a strong case for Koolhaas's being a "preservationist." Koolhaas gave the lectures at Columbia in 2004 and 2009.

The title of the book comes from Koolhaas's observation in 2004 that the interval of time keeps narrowing between the decision to save a building and its age: when preservation took off as a serious effort in the early 1800s, its targets were monuments about 2,000 years old. In 1900, they were often just 200 years old; and by the 1960s, the gap was as short as 20 years. Similarly, the definition of architecture worth keeping has become more inclusive-from Classical temples to department stores, amusement parks, even concentration camps. "We are living in an incredibly exciting and slightly absurd moment, namely [one in which] preservation is overtaking us," Koolhaas says. But he maintains the movement is limited by being "dominated by the lobby of authenticity, ancientness, and beauty."

In his 2009 lecture, Koolhaas argues that, 30 years ago, "architecture was a very serious effort" and "buildings were not luxury items" but "necessary." And now that the derisory label "starchitecture" is slapped onto so many buildings, including CCTV, he avows that "preservation is, for us, a type of refuge from this term."

In his later essay, Otero-Pailos analyzes five key principles he found in Koolhaas's lectures and other statements to form what he calls a "retroactive manifesto" for the architect: "1) Starchitecture is dead; 2) New forms are no longer relevant; 3) Preservation is architecture's saving retreat; 4) Preservation creates relevance without new forms and 5) Preservation is architecture's formless substitution." (This final tenet, Otero-Pailos explains, means that "preservation's mode of creativity is not based on the production of new forms but rather on the installation of formless aesthetics" as seen in OMA's Ruhr Museum renovation in Essen, Germany (2010).

But what if Koolhaas's thoughts have gradually shifted from those of 2004 and 2009? Not discussed in this GSAPP publication is Koolhaas's lecture at Harvard in July 2013 (now on YouTube). Here Koolhaas laments the confusion in preservation. Increasingly, its "artificiality and inauthentic architecture" results in "quasi-historical buildings" and a "faux monumentality," exemplified by the reconstruction of Dresden. At the end, Koolhaas makes clear that these efforts are leading to a "terrible situation"-"the end of the new." Despite this caveat, Koolhaas's ideas of the last decade, along with Otero-Pailos's "supplement," offer intriguing reading about the vagaries of preservation.