Successful simultaneous measurements of significant parameters of lightning strikes to the Canadian National (CN) Tower in Toronto have been performed since the summer of 1991. Three 10-bit 10-ns computer-controlled double-channel digitizers, with long segmented memory, have simultaneously captured the current derivative at the CN Tower and the corresponding electric and magnetic fields 2.0 km north of the tower. Lightning flashes to the tower were videotaped from two mutually perpendicular directions for the purpose of constructing a three-dimensional image of the lightning path. Furthermore, the return stroke velocity, a parameter also needed for the analysis of lightning radiation models, has been measured by a computer-controlled photodiode system. In this paper all relevant parameters for a CN Tower lightning stroke, observed on August 17, 1991, are shown and analyzed. ¿ American Geophysical Union 1995