At the foot of the slope beyond S. Onofrio were the horti Agrippinae, which occupied the present site of St. Peter's and extended to the Tiber, from which they were separated by a portico. These gardens were owned by Agrippina, and at her death in 33 A.D. came into the possession of her son Caligula. Thenceforth they were a part of the imperial property, and were a favorite resort of later emperors, especially of Nero and Elagabalus.
The north boundary of the horti Agrippinae appears to have been the via Cornelia, and from this street east extended the horti Domitiae, which belonged to Domitia, the sister of Nero's father. (Platner)
Vincenzo Fasolo, "The Campo Marzio of G. B. Piranesi".
outline - long[est] axis
the Horti Agrippinae
--the introduction of the non-orthagonal approach.
The Longest Axis / The Axis of Life
eros et thanatos
In G.B. Piranesi's Ichnographia Campus Martius, he positions the horti Agrippinae along the Tiber right where the river makes an almost ninrty degree bend. Judging from the description in The Times article, it seems that Piranesi's positioning is close to accurate.