It may be the start of a new year, but it is also the end of an era. Thanksgiving morning, we learned of the death of Robert A.M. Stern, 86. Just eight days later, on December 5, as we were closing this issue, Frank Gehry died, at the age of 96. Both were titans of architecture, but they could not have been more different. For Stern, history was paramount, forming the foundation of what he taught and wrote, and of the buildings he designed—an attempt, one might say, to bring back the spirit of a much-loved (for Stern) but bygone age. Gehry, who achieved a level of fame rivaled only by that other Frank, was a radical. Rejecting what came before him, he embraced novel materials and advanced technology to produce forms we had never seen before. In this issue, we pay tribute to both architects, whose remarkable careers, matched by outsize personalities, will continue to characterize the work of their respective firms.

At 90, Norman Foster is still going strong as part of that industrious generation of architects. He followed yet another path—one exuberantly exemplified by his latest building, the Zayed National Museum of the United Arab Emirates in Abu Dhabi. It is among a cluster of museums in the capital’s Saadiyat Cultural District, including Gehry’s much-delayed but under-construction Guggenheim.