Rugby union is the national sport of Wales an is considered a large part of national culture. Rugby is thought to have reached Wales in the 1850s, with the national body, the Welsh Rugby Union (WRU) being formed in 1881. The national team play out of the WRU-owned Millennium Stadium, and compete annually in the Six Nations Championship, as well as having competed at every Rugby World Cup. Wales are ranked as a tier-1 nation by the International Rugby Board (IRB). The main domestic competition in Wales is the Magners League, in which Wales have four sides, in the competition which is also contested by Irish and Scottish clubs. Welsh teams also compete in the European Heineken Cup and European Challenge Cup.