When the library's windowless, concrete bunker-like predecessor closed for renovations in 2007, only visionaries could have imagined this transformation. Evidently, that's just what the folks at architecture firm LiRo turned out to be. Its staff created an elegant, luminous space with copious, tiered windows and a light-as-air, modern feel. At the far end of the children's room, kids encounter its "tree," the focal point for storytimes and performances, thanks to a "grassy" (green-carpeted) mini-amphitheater at its base. Equally stunning is the huge watercolor rendering of the High Bridge aqueduct, the oldest bridge in the city and the neighborhood's namesake. The careful placement of the arched doorway within the arch of the mural creates a playful trompe l'oeil effect that's bound to wow mini librarygoers. 78 W 168th St at Woodycrest Ave, Bronx (718-293-7800, nypl.org).