here is a fairly rare type
Constantinopolis
Commemorative
A.D. 337- 340
CONSTANTINOPOLIS; laureate, helmeted, wearing imperial mantle, holding scepter.
VICTORIA AVG; Victory stg. on prow, holding wreath and palm.
in exergue R ✶ E
RIC VIII Rome 31
When I found mine in a dealer's hoard in 1989 I was very pleased, especially because I bought four Constantinian coins from the hoard and this one was reckoned as a normal CONSTANTINOPOLIS. I have not seem many offered since then, although Victor has the one above on vcoins now.