This appears to be the walk that runs along the top of the Spanish steps, in front of the church. I remember reading that Joseph Severn and John took walks there during the early weeks in Rome, when John was still well enough to get out and about. It looks like it would have been a lovely walk.
http://commons.wikimedia.org/wiki/File:Fran%C3%A7ois_Marius_Granet_-_La_Trinit%C3%A9-des-Monts_et_la_Villa_M%C3%A9dicis,_%C3%A0_Rome.jpg
