The Museum of Modern Art has returned to Manhattan after a two-year renovation and expansion. Among the major changes patrons are likely to cheer are an expanded lobby with a new entrance on 54th Street; a lovely sculpture garden that resurrects architect Philip Johnson's 1950s garden design, an entire floor (#2) devoted to contemporary art, a gallery space designed exclusively for video and media (it's been soundproofed), and a sixth-floor gallery space with skylights and 18-foot ceilings that will house temporary exhibitions. There's much more to the renovation than we can divulge here, so go and see for yourself. COST: $20 adults, $16 seniors, $12 students. Children under 16 free. Free Friday evenings 4 p.m. - 8 p.m.