The
Pontine Marshes, termed in
Latin Pomptinus Ager by
Titus Livius,
Pomptina Palus (singular) and
Pomptinae Paludes (plural) by
Pliny the Elder, today the
Agro Pontino in
Italian, is an approximately quadrangular area of former
marshland in the
Lazio Region of central Italy, extending along the coast southeast of Rome about from just east of
Anzio to
Terracina (ancient Tarracina), varying in distance inland between the
Tyrrhenian Sea and the Volscian Mountains (the
Monti Lepini in the north, the
Monti Ausoni in the center, and the
Monti Aurunci in the south) from The northwestern border runs approximately from the mouth of the river
Astura along the river and from its upper reaches to
Cori in the Monti Lepini.