| The county is bounded to the north by Brecknockshire, east by Monmouthshire, south by the Bristol Channel, and west by Carmarthenshire and Carmarthen Bay. |
| Brecon, the county town of Brecknockshire, lies upon the River Usk, and was formerly defended by walls and gates. |
| The Brecon circuit served the counties of Brecknockshire, Radnorshire and Glamorgan while the Carmarthen circuit served Cardiganshire, Carmarthenshire and Pembrokeshire. |
| Some of the cells are remaining to this day, as at Ty Iltud, in Brecknockshire. |
| Brecknockshire prefers the Spreading bellflower, while Cardiganshire opts for the Bog-rosemary. |
| The Lord Lieutenant of Brecknockshire and Lord Lieutenant of Radnorshire were appointed as Lieutenants. |
