Alexandria Troas — A settlement in Troas
Alexandria Troas is the site of an ancient Greek city situated on the Aegean Sea near the northern tip of Turkey's western coast.

According to Strabo, this site was first called Sigeia; around 306 BC Antigonus refounded the city as the much-expanded Antigonia Troas by settling the people of five other towns in Sigeia, including the once influential city of Neandreia. It did not receive its name until its name was changed by Lysimachus to Alexandria Troas, in 301 BC, in memory of Alexander III.

As the chief port of north-west Asia Minor, the place prospered greatly in Roman times, becoming a "free and autonomous city" as early as 188 BC, and the existing remains sufficiently attest its former importance. In its heyday the city may have had a population of about 100,000. Strabo mentions that a Roman colony was created at the location in the reign of Augustus, named Colonia Alexandria Augusta Troas. Augustus, Hadrian and the rich grammarian Herodes Atticus contributed greatly to its embellishment; the aqueduct still preserved is due to the latter. Constantine considered making Troas the capital of the Roman Empire.

It is unknown when the city was destroyed, but it continued to exist at least into thr 10th Century.

Modern location: Southeast of Dalyan, Turkey
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An AE unit struck c. AD 253-268 in Alexandria Troas
Obverse: CO TRO AV, draped and turreted bust of Tyche right; vexillum inscribed COL at shoulder

Reverse: COL AVG, horse grazing right; TRO in exergue

Diameter: 20 mm
Die Orientation: 1 H
Weight: 5.47 g

A pseudo-autonomous issue struck during the reign of Gallienus

Bellinger A486 var.
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An AE unit struck c. AD 253-268 in Alexandria Troas
Obverse: ALEX TRO, draped and turreted bust of Tyche right; vexillum inscribed CO/AV at shoulder

Reverse: COL AVG TRO, eagle, wings spread, standing right on head of bull

Diameter: 21 mm
Die Orientation: 11 H
Weight: 5.69 g
No notes for this coin
Bellinger A490; SNG Copenhagen 114
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An AE AE20 struck c. AD 253-268 in Alexandria Troas
Obverse: ALEXA TRO, turreted and draped bust of Tyche right; vexillum behind

Reverse: COL AVG, she-wolf standing right, suckling the twins Romulus and Remus; TRO in exergue

Diameter: 19 mm
Die Orientation: 6 H
Weight: 4.88 g
No notes for this coin
Bellinger A495
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An AE unit struck 211-217 AD in Alexandria Troas
Obverse: laureate, cuirassed bust right, head of Medusa on cuirass; AV.M AV__ANTONIN

Reverse: Apollo left leaning foot on pedestal, holding branch; COL A_LEXA AVG

Diameter: -
Die Orientation: -
Weight: 6.7 g
ex Gorny & Mosch
Bellinger, Troy Vgl. A 298; SNG v. Aul. Vgl. 7559.
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An AE unit struck 211-217 AD in Alexandria Troas
Obverse: ANTONINVS PIVS AV, Head of Caracalla facing right, wearing laurel wreath

Reverse: ? ALEXAN ?, Horse grazing facing right, COL in exergue?

Diameter: 22 mm
Die Orientation: 12 H
Weight: 4.43 g
Troas, Alexandria mint

The closest I could come to matching this up was by looking at sold examples, the type matches with " Bellinger A283", but the inscriptions on my coin are quite different on both sides.
Bellinger A283 var. (obv. and rev. insc.)
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An AE 22 struck AD 253-260 in Alexandria Troas
Obverse: IMP LICIN GALLIENVS, laureate, draped and cuirassed bust right

Reverse: COL AVG, horse grazing right; TRO in exergue

Diameter: 20 mm
Die Orientation: 5 H
Weight: 5.49 g
No notes for this coin
Bellinger A451
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An AE unit struck 253-260 AD in Alexandria Troas
Obverse: laureate, draped and cuirassed bust left from behind; IMP LICIN GALLIENVS

Reverse: grazing horse right; COL AVG / TRO

Diameter: 23 mm
Die Orientation: -
Weight: 9.9 g
No notes for this coin
Bellinger A451