What is "cremera"

Cremera is a Italian stream in Lazio (and previously in Etruria) which runs past Sacrofano, Formello, and Campagnano di Roma before falling into the Tiber about north of Rome. It connects to the Tiber just as the Via Flaminia intersects the Grande Raccordo Anulare highway, on the proximity of the Labaro Roma Nord railway station, where an ancient Roman bridge is. The identification with the Fosso della Valchetta is fixed as correct by the account in Livy ii. 49, which shows that the Saxa Rubra were not far off, and this we know to be the Roman name of the post station of Prima Porta, about from Rome on the Via Flaminia. It is famous for the defeat of the three hundred Fabii, who had established a fortified post on its banks.