Dan Goodwin wanted to set a record by climbing the world's tallest structure, Toronto's 1,815-foot Canadian National Tower. Unfortunately officials, concerned that microwaves emitted near the top of the tower might prove hazardous to his health, refused to let him ascend more than 1,125 feet. The solution? Goodwin, using only his chalk-covered hands and rubber-soled feet, climbed the 1,125 feet twice in three hours and 19 minutes. "I knew I could do it—it was a question of how fast," says the Marin County, Calif.-based adventurer, who in 1981 used hooks and suction cups to climb Chicago's 1,454-foot Sears tower—without permission. This time Canadian officials consented to his ascent. Says Goodwin, 30, "When I told them I didn't plan to use ropes, their mouths dropped."