Domitius Domitianus, AR argentius, Alexandria, in the name of Diocletian. AD 295, 3.24 g. 

DIOCLETIANVS AVG, laureate head right, with facial features of Domitius Domitianus.
PROVIDENTIAE AVGG, four tetrarchs sacrificing over a tripod before the archway of a six-turreted enclosure. 

A in left field.
Mintmark ALE.

Type RIC VII 7a.

With permission of Numismatica Ars Classica - Auction 78, Lot 1122, May 2014.
RIC only lists this type with a Delta in the right field as described by Pink in Numis. Zeitschrift 1930, but a number of varieties are known.