Map - Port Laoise (Portlaoise)

Portlaoise, or Port Laoise , is the county town of County Laois, Ireland. It is located in the South Midlands in the province of Leinster.

The 2016 census shows that the town's population increased by 9.5% to 22,050, which was well above the national average of 3.8%. It is the most populous and also the most densely populated town in the Midland Region, which has a total population of 292,301 at the 2016 census. This also makes it the fastest growing of the top 20 largest towns and cities in Ireland.

It was an important town in the medieval period, as the site of the Fort of Maryborough, a fort built by English settlers in the 16th century during the Plantation of Queen's County.

Portlaoise is fringed by the Slieve Bloom mountains to the west and north-west and the Great Heath of Maryborough to the east. It is notable for its architecture, engineering and transport connections. On the national road network, Portlaoise is located 94 km west-southwest from Dublin on the M7, 170 km north-east from Cork on the M8/M7 and 114 km east-northeast from Limerick on the M7.

It was once known for the manufacture of iron and steel buildings, tennis balls, rubber seals, tyres, electrical cabling, and Ireland's first aircraft. Today Portlaoise is a commercial centre, with the economy dominated by the service sector, and a hub of shopping, transport, and events for the surrounding catchment.

The site of the present town is referred to in the Annals of the Four Masters, written in the 1630s, as Port Laoighisi. The present town originated as a settlement around the old fort, "Fort of Leix" or "Fort Protector", the remains of which can still be seen in the town centre. Its construction began in 1548 under the supervision of the then Lord Deputy Sir Edward Bellingham, in an attempt to secure English control of the county following the exile of native Celtic chieftains the previous year. The fort's location on rising ground, surrounded to the south and east by the natural defensive barricades of the River Triogue and an esker known locally as 'the Ridge', greatly added to its strategic importance.

The town proper was established by an Act of Parliament during the reign of Queen Mary in 1557. Though the early fort and its surrounding settlement had been known by a number of names, such as Governor, Port Laois, Campa and Fort Protector, the new town was named Maryborough (IPA [ˈmarbrə]) and the county was named Queen's County in Mary's honour. In about 1556, Portlaoise acquired its first parish church—Old St Peter's—situated to the west of Fort Protector. Although first built as a Catholic church, due to Queen Mary's re-establishment of Roman Catholicism, the church was used for Protestant services after the accession to the English throne of Mary's half-sister, Elizabeth.

The area had been a focus of the rebellion of Ruairí Óg Ó Mórdha, a local chieftain who had rebelled and had lost his lands, which the Crown wanted to be settled by reliable landowners. For the next fifty or so years, the new English settlers in Maryborough fought a continual, low-scale war with the Gaelic chieftains who fought against the new settlement. The town had been burnt several times by the end of the 16th century.

Maryborough was granted a market in 1567, and then in 1570, a charter of Queen Elizabeth I raised the town to the rank of borough. This allowed the establishment of a Corporation of the Borough, a body which consisted of a burgomaster, two bailiffs, a town clerk, and a sergeant at arms, as well as various other officers, burgesses and freemen. The Maryborough Division was represented by two members in the Irish Parliament until 1800. The Act of Union ended this franchise, and it became part of the electorate of Queen's County until 1922. The town's Corporation itself existed until 1830.

In 1803–04, a new Church of Ireland church was built to replace the Old St Peter's; it was the first building to be erected on the new Market Square. The building is attributed to architect James Gandon. Other notable buildings constructed in Maryborough in the 19th century included the now-destroyed French Renaissance-style Town Hall on Market Square; the Court House on Main Street, built in 1805; the County Gaol built in 1830 to a design by William Deane Butler; and the neo-classical St. Fintan's Hospital, built in 1833 on the Dublin Road.