ES означает экскурсионный маршрут?
Кстати, может быть кто-нибудь опознает место съёмки?

The place is Piazzale San Lorenzo.
The church on the background is "Basilica di San Lorenzo fuori le mura" (built from 1200).

The line ES is for "Esterna Sinistra" [external left] that was one of the six circle lines in Rome, in italian is "Circolare".
The line ware:
ES and ED (Esterna Destra [external right] ): call also "la rossa" [the red] was most the external ring and the biggest. Set in 1931, ES was suspended in 1961 and replaced by bus (were necessary 48 buses against the 28 trams for the other), ED, in 1973 renumbered 29, suspended finally in 1975.
CS (Circolare Sinistra [circle left])and CD (Circolare Destra [circle right]): call also "la near" [the black] the internal ring ran for the most near the roman wall. Set in 1930 suspended in 1959.

And the last and smallest ring ware the 10black and 10red, ran in the area of Termini, central hospital, "La Sapienza" university and San Lorenzo district. The last line to use the two axle trams until 1964. set in 1947 suspended in 1966