What are New York City's best apartment buildings? Before 1900, it was the Dakota and the Osborne; soon after came McKim, Mead & White's 998 Fifth and the ultra-soign 820 Fifth Avenue. The roaring twenties produced true luxury: 740 Park Avenue, the art deco-inspired River House, and Rosario Candela's extraordinary 778 and 720 Park Avenue. Today, the city's skyline sparkles with palatial new buildings, such as Robert A. M. Stern's 15 Central Park...