Latium was an area of ancient Italy centering on a coastal plain that was home to the Latins. To the north of Latium was the Tiber River (and Anio). The Apennine mountains lay to the east, and the Alban Hills to the south. The Tyrrhenian Sea lay to the west. After the Latins conquered the land of the Volscians, Hernici, Aequians, and other tribes, their land became part of Latium, which now reached from Etruria to Campania.
With Augustus, Latium coupled with Campania became one of the 14 regions of Rome.
Today Lazio is approximately equivalent to ancient Latium.
More on Latium
Also see Janus, Ruler of Latium (mythological); Alba Longa.
References:
- A Smaller History of Rome, by William Smith
- Oxford Dictionary of the Classical World
- The Oxford Classical Dictionary