Thessalonica in Macedonia, 28-27 BC., Octavian, Æ22, RPC 1554.

Thessalonica in Macedonia, divus Julius Caesar and Octavian, 28-27 BC.(?),
Æ22 (20-21 mm / 8,88 g),
Obv.: ΘEOΣ , crowned head (corona civica) of Julius Caesar right; countermark on neck: ligate NK in circle of 6.5 mm (abbrev. for NIKH or NEPO KAICAP).
Rev.: ΘEΣΣAΛO-NIKEΩN, Δ (under bust) , bare head of Octavianus (Augustus) right.
RPC I 1554 ; SNG ANS 824 ; BMC 58 var. ; for countermark: Howgego GIC 625 (25 spec.) .

The Δ has been interpreted as either a denomination mark (four assaria) or, more likely, a date - year four of the Actian era (28/7 BC). The ligate NK monogram has been generally accepted as a reference to Nero (Nerwn Kaisar). This is problematic considering that Thessalonica had abundant coinages issued under Claudius and Nero, such that countermarking these quite older coins would be unlikely. Touratsoglou (Touratsoglou, Die Münzstätte von Thessaloniki in der römischen Kaiserzeit, Berlin 1988, p. 25 / 105) follows Kraay's suggestion that the NK is an abbreviation for Nike (NiKh), and was applied to the coins during celebrations of the city's 50th anniversary of its grant of liberty by the Romans. All but two of the known specimens of this countermark occur on the coins of this first issue of Thessalonica, and the wear on the countermarks is nearly identical to that of the coins, suggesting that the countermarks could not have been applied very long after the coins entered circulation.