Justinian I (527-565) AE Follis (Bronze, 40mm, 23.04g) Constantinople Dated year 13 (539/40 AD).
Obv: DN IVSTINIANVS PP AVG, helmeted and cuirassed facing bust, holding globus cruciger and shield with horseman
Rev: Large M, ANNO XIII flanking, A/CON.
Ref: DOC I 38c; Sear 163.