Pick up a late Roman bronze — a Constantine the Great follis, a Constantius II issue, a coin of Valens or Valentinian I — and flip it over.
Look at the bottom of the reverse, in the small space below the main design. In most late Roman coins, you will see a short string of letters: two, three, four, sometimes five characters. They look like a printer’s mark or a footnote at first glance. Easy to dismiss.
But these letters are something remarkable. They are a mint mark — the city’s signature on the coin — and they tell you exactly where, and by which workshop, that specific piece of metal was struck. A coin marked SMTR was made in Trier, in what is now Germany. One marked SMAL came from Alexandria in Egypt. SIS means Siscia, the Danubian frontier city in modern Croatia. SMN means Nicomedia, the eastern capital in what is now İzmit, Turkey.
Every one of those marks is a small postcard from an exact location in the Roman world. Learn to read them, and any late Roman coin becomes a pin dropped on a map of the ancient Mediterranean.
Why Mint Marks Appeared When They Did
For most of the Roman Empire’s history, mint marks were not necessary. Rome itself was the primary mint for the imperial currency, and the few provincial operations that existed were often identifiable by their style alone.
This changed in the late third century AD. As the empire fragmented under the pressure of civil wars, barbarian invasions, and economic crisis, the emperors of the era — especially Diocletian after AD 293 — established a network of regional mints to produce coinage closer to the troops who needed to be paid. By the time of the Tetrarchy, there were fourteen or more simultaneously-operating mint cities scattered across the empire, each producing coins for its local armies and provinces.
With so many mints operating at once, the state needed a way to track production. Which city struck a particular coin? Which workshop within that city? What issue or date series?
The answer was the mint mark — a short alphabetic code stamped into the design below the main figures. The system became universal around AD 294 and survived, in various forms, for more than a thousand years afterward through the Byzantine era.
Where to Look on the Coin
The mint mark appears in a specific location called the exergue — the area at the bottom of the reverse, below the main design. On many coins, the exergue is visually separated from the rest of the reverse by a thin horizontal line (called an exergue line), and the mint mark sits in the small band of space below it.
Sometimes the mark runs beneath the feet of a standing figure. Sometimes it sits below a temple, an altar, or a Roman standard. On coins with crowded reverses, the mark can also appear in the field — the blank space flanking the main figure — or even in the hands of the figure itself.
In addition to the mint mark proper, many late Roman coins also carry field marks: small symbols (a star, a crescent, a wreath, a laurel branch) that indicate specific issues within a mint’s production. A coin from Trier with a star in the left field and a crescent in the right might be from a different issue than one with no field marks at all, even though both carry the same TR or SMTR below.
How to Read a Typical Mark
A complete late Roman mint mark often has three parts:
1. The “SM” prefix (when present). Many mint marks begin with the letters SM, which stand for Sacra Moneta — “Sacred Money” or “Imperial Money,” signifying that the coin was struck under imperial authority. SMTR means Sacra Moneta Treverorum (Imperial Money of Trier). SMAL means Sacra Moneta Alexandriae. SMN is Nicomedia.
Not every mint mark has the SM prefix. It appeared and disappeared at different periods, depending on the issue and the emperor’s fashion. A coin marked simply TR or TRE is still from Trier — just an earlier or later issue when the SM prefix wasn’t in use.
2. The city abbreviation. The core of the mint mark is the city code itself — usually the first few letters of the Latin name. TR = Treveri (Trier). AL = Alexandria. SIS = Siscia. CON = Constantinople. These abbreviations are mostly intuitive once you know the Latin city names.
3. The workshop letter. Many mints had multiple workshops operating simultaneously within the same city. Each workshop — called an officina in Latin — was numbered using a letter. In western mints, officinae were usually labeled with Latin letters (A = 1st, B = 2nd, C = 3rd, and so on). In eastern mints, Greek letters were often used instead (A, B, Γ, Δ, Ε, Ϛ, for officinae 1 through 6).
So the mark SMTR-A tells you: Sacred Money, Trier mint, 1st workshop. SMAL-B means Alexandria, 2nd workshop. SMAN-Γ means Antioch, 3rd workshop (using the Greek gamma).
Understanding these three parts — prefix, city, workshop — lets you decode almost any late Roman mint mark you encounter.
One Common Confusion: CON and CONS
There’s one set of letters that catches almost every beginner: CON, CONS, and CONST.
Depending on the period and the specific coin, these can refer to two completely different cities:
- Constantinople — the eastern capital founded by Constantine the Great in AD 330. Coins from this mint are usually marked CONS or CONSP, often with a workshop letter.
- Arelate/Arelatum (modern Arles, France) — a Gallic mint that was renamed Constantina in honor of Constantine II in AD 328. After the renaming, coins from Arles were marked CON, CONS, or KON.
This renaming has confused collectors for centuries. A coin marked simply “CON” from AD 330-340 could be from either city, and the distinction usually has to be made on stylistic grounds or by consulting references for the specific issue.
For most practical purposes:
- If the coin looks eastern (Greek letters, typically later Constantinian style), CON = Constantinople
- If the coin looks western (Latin officina letters, Gallic style), CON = Arelate/Arles
- When in doubt, check a reference like the RIC (Roman Imperial Coinage) volumes for the specific emperor.
Gold and Silver — Special Marks
Precious metal coins of the late empire often carried additional marks indicating their purity.
CONOB — seen on gold coins struck at Constantinople — doesn’t just mean “Constantinople.” The OB suffix stands for obryziacum, the Latin term for refined pure gold. CONOB therefore signifies “Constantinople mint, refined gold” — essentially a purity guarantee. You’ll see it on Byzantine solidi for centuries after the fall of the Western Empire.
Similarly, silver coins sometimes carry PS suffixes: pusulatum, meaning refined silver. These marks assured merchants that the coin met the precious-metal standard of the time — important in an era when debasement had become a recurring problem.
Mints Represented in the Collection
Several of the major Roman mint cities are represented in the collection, and looking at specific coins makes the mint-mark system much easier to understand in practice.
Rome — the eternal mint, operational from the Republic through the Byzantine period. Coins from Rome carry marks like R, RM, ROM, or VRB ROM (Urbs Roma — “the City of Rome”). You can see examples in the collection’s Rome-minted coins, and they span many centuries.
Trier (Treveri) — the western imperial capital in Gaul, one of the most productive mints of the late empire. Marked TR, TRE, SMTR. Trier-minted examples in the collection include the Galerius Follis of Genius from the early Tetrarchy. Browse all Trier-minted coins in the collection →
Siscia — a major Danubian frontier mint serving the Balkan legions. Marked SIS, SISC, SMSIS. The Probus Antoninianus of Roma in the collection is a good example of a Siscia issue. All Siscia-minted coins →
Antioch — the great eastern mint serving the armies on the Parthian and Sasanian frontiers. Marked AN, ANT, SMAN, often with Greek officina letters. The Constantine I Follis with Two Soldiers (Antioch) bears a distinctive Antioch mark. All Antioch coins →
Alexandria — the Egyptian mint, known for distinctive provincial coinage and late Roman folles. Marked AL, ALE, SMAL. In the collection, the billon tetradrachms of Aurelian and Gordian III are distinctive Alexandrian products. All Alexandrian coins →
Londinium — the short-lived British mint, operational only from about AD 287 to 324. Marked L, LN, LON, ML, MLN, PLN. The Constantius I Chlorus Follis in the collection is a London-minted example. All Londinium coins →
Constantinople — the new eastern capital from AD 330 onward, eventually the last major Roman mint. Marked CON, CONS, CONSP. All Constantinople-minted coins →
Thessalonica — the Balkan mint serving the central Greek provinces. Marked TES, TS, THS, THES. All Thessalonica-minted coins →
Heraclea — an eastern mint on the Sea of Marmara, serving the Thracian armies. Marked H, HT, HER, SMH. All Heraclea-minted coins →
Cyzicus — the other major mint on the Sea of Marmara, operating in the east Propontis. Marked K, KV, KVZ, SMK. All Cyzicus-minted coins →
Complete Reference Table
For lookup purposes, here is the full list of major Roman mints, with their common mint marks and modern locations.
| Mint Mark | Latin Name | Modern Location |
|---|---|---|
| AL, ALE, ALEX, SMAL | Alexandria | Alexandria, Egypt |
| AMB, AMBI | Ambianum | Amiens, France |
| AN, ANT, SMAN | Antioch | Antakya, Turkey |
| AQ, AQVI, AQPS, SMAQ | Aquileia | Aquileia, Italy |
| A, AR, ARL, (CON, KON after AD 328) | Arelate / Constantina | Arles, France |
| BA, SMBA | Barcino | Barcelona, Spain |
| C, CL | Camulodunum | Colchester, England |
| CON, CONS, CONSP | Constantinopolis | Istanbul, Turkey |
| K, KAR, KART | Carthago | Near Tunis, Tunisia |
| CVZ, CYZ, K, KV, KVZ, SMK | Cyzicus | Kapıdağ, Turkey |
| H, HT, HER, HERACL, SMH | Heraclea | Marmara Ereğlisi, Turkey |
| L, LN, LON, ML, MLN, PLN | Londinium | London, England |
| LD, LG, LVG, LVGD | Lugdunum | Lyon, France |
| MD, MED | Mediolanum | Milan, Italy |
| N, NIC, NICO, NIK, SMN | Nicomedia | İzmit, Turkey |
| OST, MOST | Ostia | Near Rome, Italy |
| RV, RVPS | Ravenna | Ravenna, Italy |
| R, RM, ROM, ROMA, VRB ROM | Roma | Rome, Italy |
| SIS, SISC, SMSIS | Siscia | Sisak, Croatia |
| SD, SER, SMSD | Serdica | Sofia, Bulgaria |
| SM, SIR, SIRM | Sirmium | Sremska Mitrovica, Serbia |
| TE, TES, TS, THS, THES | Thessalonica | Thessaloniki, Greece |
| T, TI, SMT | Ticinum | Pavia, Italy |
| TR, TRE, SMTR | Treveri | Trier, Germany |
When There Is No Mint Mark
For coins minted before the Tetrarchy — most denarii of the early empire, the sestertii of the high imperial period, the antoniniani of the third-century crisis — there is usually no explicit mint mark. Attribution must then be made on the basis of:
- Style — distinctive workshop styles for portraits, letter forms, and engraving details
- Fabric — the physical characteristics of the flan (weight, thickness, color) can indicate regional production
- Metrology — slight weight standards can distinguish eastern from western issues
- Historical context — where was the emperor at the time? Mints often traveled with the imperial court, and an emperor who spent a year in Antioch usually struck coins there
This is harder work than reading a clear mint mark, and it’s why attributions of pre-Tetrarchic coins sometimes say “Rome or Lyon” rather than a definite mint. For difficult cases, the standard references are the RIC (Roman Imperial Coinage) catalog series for the imperial period, and David Sear’s Roman Coins and Their Values for a broader overview.
What the Marks Really Tell You
Every mint mark is a small miracle of bureaucratic precision.
Think about what it represents: somewhere in the Roman Empire, in a specific year, in a specific city, in a specific workshop within that city, a specific team of workers produced a specific coin. The chain of documentation is essentially intact. Seventeen hundred years later, you can still read that provenance from two or three letters below the emperor’s feet.
No other artifact of the ancient world gives you this kind of location data at scale. An ancient vase might be attributable to a region; a statue might be tied to an artist’s workshop. But Roman coins — millions of them — carry explicit, standardized mint marks that place them unambiguously in time and space.
When you learn to read them, you stop seeing Roman coins as generic imperial portraits. You start seeing a scattered production system — Alexandria and Antioch in the east, Rome and Ravenna in the Italian heartland, Trier and Lyon in Gaul, Siscia and Thessalonica in the Balkans, Londinium on the empire’s northwestern edge — all of them producing silver and bronze that flowed along the Roman roads to soldiers and tax collectors and market stalls.
Every late Roman coin you hold came from a specific one of these places. The mint mark tells you which.
To explore the Roman coinage by mint location, browse the collection by mint or view the timeline. To understand the broader system these coins were part of, see our guide to Roman coin denominations. For the physical process that produced these coins, read how ancient Roman coins were made. And for one of the most remarkable preserved groups of mint-marked coinage ever found, see our post on the Rauceby Hoard.
