A branch line?

Here at Piazza di Porta San Lorenzo scholars surmise the start of the Rivus Herculaneus, a branch
of the Aqua Marcia heading towards the Caelian and Porta Capena (see Frontinus 19). Now one can
see the Aurelian wall with the channel of the Acqua Felice annex and on the background the
ancient Porta Tiburtina.