June 1981 I purchased a large poster-size reproduction of the Ichnographia Campus Martius.
April 1987 I purchased a complete ArrisCad system.
May 1987 I commensed redrawing the Ichnographia Campus Martius via cad--a personal project/endeavor.
Copious visual study and minute measurment of all the plans within the Ichnographia Campus Martius brought about my awareness of Piranesi's atypical delineations around the (unlabeled) Circus of Caligula and Nero.
By 1994 the plans of the Vatican valley are redrawn.
Sometime 1998 the University of Pennsylvania Fine Arts Library catalogue becomes available online. Among the holdings of the Rare Book Room is a 1762 edition of Piranesi's Il Campo Marzio.
14 May 1999 I go to the Fine Arts Library to examine an actual print of the Ichnographia Campus Martius.