| Dierna | |
|---|---|
  Location within Romania | |
| Alternative name(s) | Tierna [1] |
| Known also as | Castra of Orșova |
| Founded during the reign of | Trajan |
| Place in the Roman world | |
| Province | Dacia |
| Administrative unit | Dacia Apulensis |
| Administrative unit | Dacia Superior |
| Directly connected to | Praetorium |
| Structure | |
| — Stone structure — | |
| Size and area | 64 m × 54 m (0.35 [2] ha) |
| Stationed military units | |
| — Legions — | |
| — Cohorts — | |
| I Brittonum milliaria[3] | |
| Location | |
| Coordinates | 44°44′18″N 22°24′28″E / 44.7382°N 22.40764°E |
| Altitude | 85 m (279 ft) |
| Town | Orșova |
| County | Mehedinți |
| Country |  Romania |
| Site notes | |
| Condition | Ruined |
Dierna was a city and fort in the Roman province of Dacia, located beneath the present-day town of Orșova, Romania. The vicus later grew into a city.
