I believe the largest is Casement Park, a Gaelic Athletic Association stadium in West Belfast (home to the Antrim Gaelic Football and Hurling teams), which holds 32,600. Other large stadiums are Windsor Park, (home of Linfield Football Club and the Northern Ireland Football team) which holds 20,000, and Ravehill Stadium (Home of the Ulster Rugby team), which holds 12,300.
Twickenham
Post Fiji Stadium
London Irish Rugby Club, Madejski Stadium
There is no national rugby stadium. Nowadays, Argentina is using VELEZ SARSFIELD stadium for their international test matches.
Recreation Ground AKA ' The Rec'
Each New Zealand city has its own rugby stadium and the NZ Rugby Union doesn't have an official stadium of its own, but the premier New Zealand stadium is probably Eden Park in Auckland as Auckland has the largest population base and is where the World Cup final was held in 1987 and where the World Cup final will be held in 2011.
The national stadium is Estádio do Jamor, and the largest stadium is Estádio da Luz (Benfica's home)
for which country?
National Stadium (aka the Bird's Nest)
There is no special national football stadium in germany. The stadiums/cities for games of the national team change.
The kangaroos.
All Blacks