Spanning 96th Street's Great Divide Ninety-sixth Street was long the border between the Upper East Side and El Barrio, Spanish Harlem. To the north, the train tracks beneath Park Avenue leapt aboveground, and Carnegie Hill's regular grid and uniform prosperity gave way to a patchwork of public housing and poverty. Today, the old divide is less visible, and the blocks to its north are intriguingly animated by contrasts and surprises. ALONG FIFTH AVENUE, elegantly fronted apartment buildings, medical complexes and museums run in a virtually continuous row up to 110th Street. There, 1 Museum Mile, a luxury condo designed with funky trapezoidal windows by Robert A. M. Stern Architects, will eventually house the Museum for African Art. RAPHAEL MONTAÑEZ ORTIZ, an avant-garde artist, founded El Museo del Barrio in 1969 to introduce the neighborhood's Puerto Rican culture into the city's school curriculums. It moved from one public school to another until landing in its current home, on 104th Street, in the mid-1970s; its collection now includes more than 6,000 Latin American artworks. The building was once an orphanage, and its charming Heckscher Theater, decorated in the 1920s with fairy tale murals intended to delight young foundlings, dates from that time. OPPOSITE THE MUSEUM, fin de siècle gates open onto the Central Park Conservatory Garden. The Italian, French and English sections have their own horticultural moods. At the heart of the English garden is a fountain dedicated to the author Frances Hodgson Burnett; the bronze boy and girl could be straight out of her book, "The Secret Garden." Plenty of real children come to enjoy the blooms. Abdoulaye Fall, from Senegal, brings his son Elijah, 9, after school. "He likes to run among the fountains," he said. THE CARVER HOUSES, a 1950s public housing project named for George Washington Carver - who, born a slave, became director of agricultural research at Tuskegee Institute - stretches across 14 acres along Madison Avenue, from 99th Street to 106th. On Park Avenue, a stone viaduct supporting elevated train lines further disrupts the usual street pattern. But Lexington's streets are bustling, and community gardens fill formerly vacant lots. COLORFUL MOSAIC FLOWERS welcome readers to La Casa Azul, a Latino book shop on 103rd Street, between Lexington and Park Avenues. This weekend, Aurora Anaya-Cerda will celebrate her store's first anniversary with an exhibition of five artists" interpretations of Frida Kahlo in the gallery space one floor below. Outside, there's a back garden for other cultural programs. The P.S. 109 building, at 99th Street, is becoming an "Artspace" with affordable housing for artists and 10,000 square feet for community arts organizations and nonprofits. But change brings loss as well as opportunity. With this in mind, the East Harlem Cafe will host East Harlem Preservation's annual fund-raiser on June 5.