Yale Campus Tours, Yale Visitor Center, 149 Elm St., New Haven. Student-led walking tours of Yale Campus, last 1 hour and 15 minutes and covers history, architecture and student life. Visitors see the Old Campus, several residential colleges, Sterling Memorial Library and other locations of interest. Maps of the campus are available at the Center. Free. Center Hours Monday-Friday 9 a.m.-4:30 p.m.; Saturday & Sunday 11 a.m.-4 p.m. Tours Monday-Friday 10:30 a.m. & 2 p.m.; Saturday & Sunday 1:30 p.m. 203-432-2300, yale.edu/visitor Self-Guided Tours: Purchase a copy of the Blue Trail map, which