Over the years, the 1911 Beaux-Arts main branch of the New York Public Library (NYPL), now officially named the Stephen A. Schwarzman Building, by Carrère & Hastings has morphed and been modified internally to accommodate changing user needs and logistical demands. But changes can involve missteps. So it comes as a relief that for the most recent phase of this landmark’s ongoing renovation, the Dutch firm Mecanoo, as design architect, and Beyer Blinder Belle (BBB) as the preservation architect, have carried out sensitive exterior and interior interventions that enhance its circulation and accommodate expanded programmatic requirements.