One of the city’s most unusual new buildings is under construction on the Upper East Side, where the Rockefeller University is expanding its York Avenue campus by decking over the Franklin Delano Roosevelt Drive. When a visitor would stand atop the high-perched, river-facing promenade, the lawn beneath their feet would conceal two stories of state-of-the-art research labs, spanning three-and-a-half city blocks, with six lanes of traffic running directly beneath. The $500 million Niarchos Foundation–Rockefeller River Campus is on its way to housing one of the city’s largest, and most unusual, green roofs, designed with the high-concept urban spirit of layering buildings, infrastructure, and public space.