I just found this campgate as well. Instead of the pattern in top, as the coin I mentioned previously
http://www.lateromanbronzecoinforum.com/index.php/topic,1315.msg3709.html, it has the same decoration in the base in this example from Wildwinds:
Constantius II, AE3, 328-329, Nicomedia,
FL IVL CONSTANTIVS NOB C, laureate, draped, cuirassed bust left.
PROVIDEN-TIAE CAES dot, Campgate with six layers, two turrets, no doors, star above,
decorated base.
Mintmark SMNS.
RIC VII Nicomedia 158; Sear 17650.