Why is the ninth month called September?
basic gold monetary unit of ancient Rome and the Roman world. It was first named nummus aureus ("gold money"), or denarius aureus, and was equal to 25 silver denarii; a denarius equaled 10 bronze asses. (In 89 BC, the sestertius, equal to one-quarter of a denarius, replaced the bronze ass as a unit of account.) In Constantine's reform of AD 312, the aureus was replaced by the solidus as the basic monetary unit