Northern Irish football clubs compete in European tournaments. Northern Irish football clubs have competed in European football competitions since 1957, when Glenavon became the first Northern Irish club to do so in the 1957-58 season. Northern Ireland has been represented in European tournaments by 16 different clubs. Linfield are the most successful club from Northern Ireland, having won the UEFA Cup twice. Of the 16 clubs that have represented Northern Ireland in Europe, 12 are still active. They are: Ards, Armagh City, Belfast Celtic, Ballyclare, Glentoran, Linfield, Millwall, Portadown, Sligo Rovers, St Patrick's Athletic, and Warrenpoint Town. Seven of these clubs are based in Belfast. The other five clubs are spread across Northern Ireland. Armagh City, Belfast Celtic, Glentoran, Linfield, and Sligo Rovers are all based in Northern Ireland. Millwall and Portadown are both based in England but they play their home games in the UK's lower divisions (Millwall plays in the English Championship, while Portadown plays in the National League). St Patrick's Athletic is based in Dublin but they also play in the Premier Division (the top division) of the Airtricity League (which is the highest level of competition in Republic of Ireland football). Warrenpoint Town are based in County Down and they play in the NIFL Premiership (the top league in Northern Ireland).