A nice piece with visible remnants of silver plating.
Obverse: head of Augustus in laurel wreath, to the right, in the rim legend:
CONSTAN-TINVS AVG;
Reverse: camp gate of 6 rows of bricks, with open gate, in the rim legend:
PROVIDEN-TIAE AVGG; in section SMALB;
Bronze, diameter 18.5 mm, weight 3.51 g, axis 5 h.