This coin has a dot in the bottom of the doorway, which I would consider dismissing as merely a centering dot; but it is placed too low for that and the top brick over the doorway has a proper centering dot.
Constantine I
A.D. 324-5
19x21mm 3.3gm
CONSTANT-INVS AVG; Laureate bust
PROVIDEN-TIAE AVGG; camp gate with two turrets and star between them, dot in bottom of doorway.
in ex. PLON
RIC VII London 293 var