Longford is the county town of County Longford in Ireland. It has a population of 10,008 according to the 2016 census. It is the biggest town in the county and about one third of the county's population lives there. Longford lies at the meeting of Ireland's N4 and N5 National Primary Route roads, which means that traffic traveling between Dublin and County Mayo, or north County Roscommon passes around the town. Longford railway station, on the Dublin-Sligo line, is used heavily by commuters.

The Corlea Trackway Visitor Centre is located near to Longford, in Keenagh. The Centre houses an Iron Age bog road which was built in 148 BC across the boglands in proximity to the River Shannon. The oak road is the largest of its kind to have been uncovered in Europe and was excavated over the years by Professor Barry Raftery of University College Dublin. Inside the building, an 18-metre stretch of preserved road is on permanent display in a specially designed hall with humidifiers to prevent the ancient wood from cracking in the heat. Bord na Mona and the Heritage Service have carried out conservation work on the surrounding bog to ensure that it remains wet and that the buried road is preserved. There are other historical artifacts and some exhibits at the centre.

St. Mel's Cathedral in the town features several stained glass windows by Harry Clarke studios. These include one of his earliest works The consecration of St. Mel as Bishop of Longford which was exhibited at the RDS Annual Art Industries Exhibition in 1910, where it received second prize. It was also exhibited at The Arts and Crafts Society of Ireland fourth exhibition in the same year. The Cathedral was extensively damaged in a fire on Christmas Day 2009. St. Mel's Cathedral remained closed for exactly five years following the fire while it was the centre of one of the largest restoration projects undertaken in Europe. It reopened for services at midnight mass on Christmas Eve 2014 and has since become a significant tourist attraction. The two most intricated stained-glass windows in the transepts of the Cathedral have been faithfully restored - these depict St Anne and the Resurrection.

Longford town has a 212-seat theatre called Backstage Theatre just outside of the town, and a four-screen multiplex cinema, with restaurants. The mix and quality of housing is extensive and the Rural Renewal Scheme (1999-2006) has ensured that a steady supply of residential development has come about. Longford town has a decentralized government department which employs approximately 300 people and a further 130 are employed at the Irish Prison Service's headquarters in the Lisamuck area of the town. The Prison Service HQ has a sculpture by artist Remco de Fou which, apart from the Spire in Dublin is the largest piece of sculpture in Ireland. Connolly Barracks once employed approximately 180 soldiers, many of whom were involved in UN peace-keeping duties, until the barracks closed in January 2009.

The town serves as the cathedral town of the Roman Catholic Diocese of Ardagh and Clonmacnoise. St Mel's Cathedral, dedicated to Saint Mel, the founder of the diocese of Ardagh, was designed by architect John Benjamin Keane, who also designed St Francis Xavier's Church on Gardiner Street in Dublin.

There are a number of portal dolmens located around Longford.