| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Old Mountain | city | Donegal | Ireland | 55.20 | -7.49 | 830 | 1771 |
| Old Town | city | Donegal | Ireland | 55.08 | -7.61 | 29 | 1857 |
| Old Town | city | Donegal | Ireland | 54.94 | -7.74 | 246 | 14526 |
| Oldtown | city | Donegal | Ireland | 55.12 | -8.11 | 252 | 1255 |
| Owenea Bridge | city | Donegal | Ireland | 54.78 | -8.41 | 75 | 1080 |