Question: Where is linfield football club based?

Context paragraphs:
Billy Wilson (footballer, born 1936): William "Billy" Wilson (born 23 September 1936) is a former professional footballer from Northern Ireland.  He played as a wing half.  He started his career with his hometown club, Portadown, and made his debut for the club at the age of 16.  In 1955, Wilson moved to England to join Football League First Division side Burnley and initially played in the reserves.  He made his first appearance for the senior team in the 0–1 defeat to Blackpool on 1 May 1957, alongside fellow debutant Jim Appleby.  Wilson played only one more match for Burnley, deputising for regular right-half Bobby Seith for the 0–7 loss against Nottingham Forest on 18 September 1957.  He was released from his contract in May 1958 and despite interest from Crewe Alexandra and Notts County, he returned to Northern Ireland and signed for Linfield

List of Linfield F.C. players: Linfield F.C. is a semi-professional association football club based in Belfast, Northern Ireland.  The club plays in the NIFL Premiership, the highest level of the Northern Ireland Football League.  They have played at their current home ground, Windsor Park, since 1905.  Previous to this they had played at Ulsterville Avenue from 1889 until 1905 and The Meadow from their foundation in 1886 to 1889.  They were one of the founding clubs of the league in 1890, and since that time the club has competed in numerous nationally and internationally organised competitions.

Killyleagh Youth F.C.: Killyleagh Youth Football Club (also known as Killyleagh YC) is a Northern Irish, intermediate-level football club based in Killyleagh, near Downpatrick, playing in Division 1A of the Northern Amateur Football League.  The club was formed in 1960, playing in the South Belfast Youth League for one season before joining the Amateur League in 1961.  Intermediate status was achieved in 1963.  They play their home matches at the Showgrounds in Killyleagh.  Perhaps their biggest achievement of recent times was when they reached the semi-final of the Irish Cup in 2002, losing 4–0 to Linfield.  .

Linfield F.C.: Linfield Football Club is a semi-professional football club based in Belfast, Northern Ireland.  The club was founded in 1886 as Linfield Athletic Club and in 1905 moved into the current home of Windsor Park, which is also the home of the Northern Ireland national team.  The club plays in the NIFL Premiership – the highest level of the Northern Ireland Football League.  Linfield's main rival is Glentoran – the other half of Belfast's Big Two.  This rivalry traditionally includes a league derby played on Boxing Day each year, which usually attracts the largest league attendance of the season.  Linfield's average league home attendance is approximately 2,500 the highest in the division and more than double the league's overall average of about 1,000.

Supporting paragraphs: Billy Wilson (footballer, born 1936) Linfield F.C.
Answer: Northern Ireland