Linfield Football Club is a Northern Irish professional football club based in south Belfast which plays in the NIFL Premiership – the highest level of the Irish League . The fourth-oldest club on the island of Ireland, Linfield was founded as Linfield Athletic Club in March 1886 by workers at the Ulster Spinning Company's Linfield Mill. Since 1905, the club's home ground has been Windsor Park, which is also the home of the Northern Ireland national team and is the largest football stadium in Northern Ireland. The club's badge displays Windsor Castle, in reference to the ground's namesake. Historically, Linfield shared a fierce rivalry with Belfast Celtic until Celtic's withdrawal from the league for political reasons in 1949. Since then, the club's main rival has been Glentoran, with the duo known locally as the Big Two. This rivalry traditionally includes a league derby played on Boxing Day each year, which usually attracts Northern Ireland's highest domestic attendance of the season, excluding cup finals. For the 2021–22 season, Linfield's average league home attendance was approximately 2,900, the highest in the division and more than double the league's overall average of around 1,400. The team, nicknamed The Blues, is managed by former Northern Ireland international and the country's all-time record goalscorer, David Healy. Healy was appointed on 14 October 2015 to succeed Warren Feeney, following Feeney's resignation. Domestically, Linfield has been one of the most successful clubs in the world, holding several domestic and world records. The club has won 110 League titles, Irish Cups and League Cups combined, as well as numerous other domestic cup competitions – taking their trophy count to well over 200. The club was one of the eight founding members of the Irish League in 1890, won the inaugural league title, and is one of only three clubs to have gone on to compete in every season of the Irish League's top division since; a joint world record for the longest continuous membership of a national league's top division. Linfield has won a world record 56 league championships to date – more than twice as many titles as any other Northern Irish club. In the 1921–22 season, Linfield completed an unprecedented clean sweep of all seven available trophies – to date, this is the only recorded instance of a seven-trophy season being achieved in world football. In the modern era, the club won all four available domestic