Caligula
Coinage

Caligula did not change the structure of the monetary system established by Augustus and continued by Tiberius, but the contents of his coinage differed from theirs. The location of the imperial mint for the coins of precious metals (gold and silver) is a matter of debate among ancient numismatists. It seems that Caligula initially produced his precious coins from Lugdunum (now Lyon, France), like his predecessors, then moved the mint to Rome in 37–38, although it is possible that this move occurred later, under Nero. His base metal coinage was struck in Rome.

Unlike Tiberius, whose coins remained almost unchanged throughout his reign, Caligula used a variety of types, mostly featuring Divus Augustus, as well as his parents Germanicus and Agrippina, his dead brothers Nero and Drusus, and his three sisters Agrippina, Drusilla, and Livilla. The reason for the extensive emphasis on his relatives was to highlight Caligula's double claim to the Principate, from both the Julian and Claudian sides of the dynasty, and to call for the unity of the family. The sesterce with his three sisters was discontinued after 39, due to Caligula's suspicion regarding their loyalty. He also made a sesterce celebrating the Praetorian cohorts as a mean to give them the bequest of Tiberius at the beginning of his reign. Caligula minted a quadrans, a small bronze coin, to mark the abolition of the ducentesima, a 0.5% tax on sales. The output of the precious metal mints was small and his sesterces were mostly made in limited quantities, which make his coins now very rare. This rarity cannot be attributed to Caligula's alleged damnatio memoriae reported by Dio, as removing his coins from circulation would have been impossible; besides, Mark Antony 's coins continued to circulate for two centuries after his death. Caligula's common coins are base metal types with Vesta, Germanicus, and Agrippina the Elder, and the most common is an as with his grandfather Agrippa. Finally, Caligula kept open the mint at Caesarea in Cappadocia, which had been created by Tiberius, in order to pay military expenses in the province with silver drachmae.

Numismatists Harold Mattingly and Edward Sydenham consider that the artistic style of Caligula's coins is below those of Tiberius and Claudius; they especially criticize the portraits, which are too hard and lack details.
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