AR24 - Antoninus Pius L Κ

Year 20 of Antoninus Pius's reign — 156/157 AD — falls near the end of one of the longest and most administratively stable reigns in Roman imperial history, a fact that paradoxically makes Alexandrian tetradrachms from this period harder to study individually. The Alexandria mint was producing billon tetradrachms at enormous volume throughout his reign, and the alloy had been declining steadily since Nero's reduction of 64 AD. By regnal year 20, the billon content was a fraction of what it had been under earlier emperors.

Milne 2243 is a well-documented die pairing in the series.