A nicely preserved piece.
Obverse: bust of Caesar in armor and paludamentum, wearing a laurel wreath, left, in the rim legend:
FL IVL CONSTANTIVS NOB C;
Reverse: camp gate of 6 rows of bricks, with open gate, in the rim legend:
PROVIDEN-TIAE CAES-; in section NDelta;
Bronze, diameter 18 x 20 mm, weight 2.69 g, axis 12 h.