Albalonga (or Alba Longa) was a city of ancient Latium in central Italy about 19 km (12 miles) southeast of Rome. It was founded in the 12th century B.C. In Roman legend, Albalonga was founded by Ascanius, the son of Aeneas, and was later the birthplace of Romulus and Remus. Ascanius was also known as Iulus; the Julian family, ancestors of Julius Caesar, claimed descent from Iulus.

See founding of Rome

It is supposed that the papal summer palace of Castel Gandolfo stands on the site of the ancient city.