of 26 June 1971, he "juggled balls" and "pranced back and forth" as he crossed the wire on foot to the applause of the crowd below. World Trade Center walk Petit became known to New Yorkers in the early 1970s for his frequent tightrope-walking performances and magic shows in the city parks, especially Washington Square Park. Petit's most famous performance was in August 1974, conducted on a wire between the roofs of the Twin Towers of the World Trade Center in Lower Manhattan, New York City, above the ground. The towers were still under construction and had not yet been fully occupied. He performed for 45 minutes, making eight passes along the wire, during which he walked, danced, lay down on the wire, and saluted watchers from a kneeling position. Office workers, construction crews and policemen cheered him on. Planning Petit conceived his "coup" when he was 18, when he first read about the proposed construction of the Twin Towers and saw drawings of the project in a magazine he read in 1968 while sitting at a dentist's office. Petit was seized by the idea of performing there, and began collecting articles on the Towers whenever he could. What was called the "artistic crime of the century" took Petit six years' planning. During this period, he learned everything he could about the buildings and their construction. In the same period, he began to perform high-wire walking at other famous places. Rigging his wire secretly, he performed as a combination of circus act and public display. In 1971, he performed his first such walk between the towers of the cathedral of Notre Dame de Paris, while priests were being ordained inside the building. In 1973, he walked a wire rigged between the two north pylons of the Sydney Harbour Bridge. In planning for the Twin Towers walk, Petit had to learn how to accommodate issues such as the swaying of the high towers due to wind, which was part of their design; effects of wind and weather on the wire at that height, how to rig a steel cable across the gap between the towers (at a height of ), and how to gain entry with his collaborators, first to scope out the conditions and lastly to stage the project. They had to bring heavy equipment to the rooftops. He traveled to New York on numerous occasions to make first-hand observations.