Grand Slam is a general sports term applied when achieving something special.
Most common uses:
In tennis, winning the Grand Slam is winning the following four tournaments in the same year: Australian Open, French Open, Wimbledon, US Open. Those tournaments are therefore also known as the Grand Slam tournaments.
... Tate Britain and Tate Modern
Victoria and Albert Museum
Merseyside
Customs & Excise National Museum[?]
Historic Warships[?], Birkenhead
Lady Lever Art ...