NEW YORK'S SIDEWALKS: A CHOICE OF TOURS
WALKING tours of New York have come a long way since 10 years ago, when such institutions as the Municipal Art Society, the Museum of the City of New York and the Friends of Cast Iron Architecture began to take New Yorkers on ordered routes through the city's history and architecture. Today, it is possible to spend almost any weekend scrutinizing New York from the sidewalk. There have been walks through subway tunnels and across archeological digs, and bird's-eye scannings from the tops of tall buildings. The life of such New York writers as Herman Melville may provide the tour's organizing principle - or ghosts, songs, ethnic restaurants, cemetery roll-calls or poisonous plants. Few pastimes develop such a heightened awareness of familiar surroundings. ''An old teapot, used daily, can tell me more of my past than anything I recorded of it,'' Sylvia Townsend Warner has written. ''Continuity, continuity,'' she wrote, ''it is that which we cannot write down, it is that we cannot compass, record or control.'' What survives the annihilating press of time - whether a building or a neighborhood street scene - is patient and revealing.