A sophisticated tunnel has been discovered near a major sporting venue and a university in Toronto, reports said Monday, with Canada on edge over the threat of possible extremist attacks. A municipal worker was walking through woods near York University and the Rexall Center last month when he spotted a piece of corrugated metal on the ground, lifted it up and found a passageway, the public broadcaster CBC said. The tunnel was about 23 feet long and 22.5 meters tall and was lit by an electric generator. The walls and ceilings had been reinforced and tools had been left inside....