Lovely Rittenhouse Square beckons frazzled city dwellers to slow down. Today the park is the heart of upper-crust Philly. Swank hotels and modern office buildings now intrude, but the trappings of onetime grandeur remain on view in its Victorian town houses. Many treasures are tucked away here, including the Curtis Institute of Music and the Rosenbach Museum and Library, home to 130,000 manuscripts, including James Joyce's Ulysses.