County Laois in the context of "The Three Sisters (Ireland)"

County Carlow (/ˈkɑːrloʊ/ KAR-loh; Irish: Contae Cheatharlach) is a county located in the Southern Region of Ireland, within the province of Leinster. Carlow is the second smallest and the third least populous of Ireland's 32 traditional counties. Carlow County Council is the governing local authority.

The county is named after the town of Carlow, which lies on the River Barrow and is both the county town and largest settlement, with over 40% of the county's population. Much of the remainder of the population also reside within the Barrow valley, in towns such as Leighlinbridge, Bagenalstown, Tinnahinch, Borris and St Mullins. Carlow shares a border with Kildare and Laois to the north, Kilkenny to the west, Wicklow to the east and Wexford to the southeast.

Osraige (Old Irish) or Osraighe (Classical Irish), Osraí (Modern Irish), anglicized as Ossory, was a medieval Irish kingdom comprising what is now County Kilkenny, western County Laois and parts of eastern County Tipperary, corresponding to the Diocese of Ossory. The home of the Osraige people, it existed from around the first century until the Norman invasion of Ireland in the 12th century. It was ruled by the Dál Birn dynasty, whose medieval descendants assumed the surname Mac Giolla Phádraig.

According to tradition, Osraige was founded by Óengus Osrithe in the 1st century and was originally within the province of Leinster. In the 5th century, the Corcu Loígde of Munster displaced the Dál Birn and brought Osraige under Munster's direct control. The Dál Birn returned to power in the 7th century, though Osraige remained nominally part of Munster until 859, when it achieved formal independence under the powerful king Cerball mac Dúnlainge. Osraige's rulers remained major players in Irish politics for the next three centuries, though they never vied for the High Kingship. In the early 12th century, dynastic infighting fragmented the kingdom, and it was re-adjoined to Leinster. The Normans under Strongbow invaded Ireland beginning in 1169, and most of Osraige collapsed under pressure from Norman leader William Marshal. The northern part of the kingdom, eventually known as Upper Ossory, survived intact under the hereditary lordship until the reign of King Henry VIII of England, when it was formally incorporated as a barony of the same name.

Carlow (/ˈkɑːrloʊ/ KAR-loh; Irish: Ceatharlach [ˈcahəɾˠl̪ˠəx]) is the county town of County Carlow, in the south-east of Ireland, 84 km (52 mi) from Dublin. At the 2022 census, it had a population of 27,351, the twelfth-largest urban center in Ireland.

The River Barrow flows through the town and forms the historic boundary between counties Laois and Carlow. However, the Local Government (Ireland) Act 1898 included the town entirely in County Carlow. The settlement of Carlow is thousands of years old and pre-dates written Irish history. The town has played a major role in Irish history, serving as the capital of the country in the 14th century. The town is in a townland and civil parish of the same name.

The Slieve Bloom Mountains (Irish: Sliabh Bladhma; Latin: Bladinae montes) is a mountain range in Ireland. They rise from the central plain of Ireland to a height of 527 metres (1,729 ft). While not very high, they are extensive by local standards. The highest points are Arderin (527 m (1,729 ft)) (Irish: Ard Éireann) at the southwestern end of the range and Baunreaghcong (509 m (1,670 ft)) at the end of the Ridge of Capard.

The Slieve Bloom Mountains stretch from near Roscrea in the south west to Rosenallis in the north-west, forming a link between County Laois and County Offaly. Looped walking trails have been developed at six trailheads in the Slieve Blooms, Glenbarrow, Clonaslee, Cadamstown, Kinnitty, Glenafelly Forest Car Park and Glen Monicknew. Walking trails are colour-coded by difficulty. The 75 km (47 mi) Slieve Bloom Way can be accessed from any of these trailheads. The Silver River Eco Trail is near Cadamstown.