Regularly scheduled at 11:00 A.M., 2:00 P.M., and 4:00 P.M. Monday through Saturday, from the brick plaza by the Cambridge Information Booth in Harvard Square. Look for the man, with a U.S. Grant, style beard. Tours are not normally cancelled except in extreme, and severe weather; reservations are not needed; groups are welcomed. Feel free to contact us or visit our website for further information.