Powys, officially the County of Powys (Welsh: Sir Powys), is the largest principal area and county in Wales. It is named after the Kingdom of Powys which was a Welsh successor state, petty kingdom and principality that was founded during the Middle Ages following the end of Roman rule in Britain.
Modern day Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire, and a small part of Denbighshire. With an area of about 2,000 square miles (5,200 km2), it is the largest unitary authority in Wales by land area and about the same size as the country of Trinidad and Tobago. It is bordered by English counties of Shropshire and Herefordshire to the east, Gwynedd, Wrexham and Denbighshire to the north, Ceredigion to the west and Rhondda Cynon Taf, Merthyr Tydfil, Caerphilly, Blaenau Gwent, Monmouthshire and Neath Port Talbot to the south.
The county's largest towns are:
- Newtown, population 11,357
- Ystradgynlais, population 8,092
- Brecon, population 8,250
- Welshpool, population 6,664
It has the lowest population density of all the principal areas of Wales. Most of Powys is mountainous making north–south travel fairly difficult.