Lavinium was a port city of Latium, 6 km to the south of Rome, midway between the Tiber river at Ostia and Anzio. The coastline then, as now, was a long strip of beach. Lavinium was on a hill at the southernmost edge of the Silva Laurentina, a dense laurel forest, and the northernmost edge of the Pontine Marshes, a vast malarial tract of wetlands. The basis for the port, the only one between Ostia and Anzio, was evidently the mouth of the Numicus river.
The location of Lavinium has never been lost to historians nor does there appear to have been any significant break in its habitation. Today's settlement remains a walled village of medieval design, Pratica di Mare, in the comune of Pomezia.
Wikipedia https://en.wikipedia.org/wiki/Lavinium
Address 00040, Italy
Coordinates 41°39'24.674" N 12°28'40.013" E