Between 1998 and 2000 the Royal Australian Mint undertook a three-year series dedicated to the 'Coins of the 20th Century'. Each year included a different set consisting of proof silver pieces with a mintage of 15,000 sets.
This series began with the 'Milestones' set in 1998 which paid tribute to a series of coins that marked key events in Australian history: 1910 Florin (Introduction of Australian Currency), 1927 Florin (Opening of Parliament House), 1934-35 Florin (Centenaries in the South), 1937 Crown (Coronation of King George VI), 1938 Florin (Australia's 150th Anniversary), 1951 (Fifty Years of Federation), 1954 Florin (Royal Visit to Australia), 1966 Twenty Cent (Introduction of Decimal Currency), 1995 Twenty Cent (50th Anniversary of the United Nations).
In 1999 the 'Memories' set celebrated six pre-decimal reverse designs: 1918 Sixpence, 1920 Sovereign, 1930 Penny, 1939 Kangaroo Halfpenny, 1940 Shilling, and the 1942 threepence.
The series was was concluded in 2000 with the 'Monarchs' set which features portraits of the five monarchs who ruled over Australia: 1901 Sovereign (Queen Victoria), 1910 Florin (King Edward VII), 1911 Florin (King George V), 1937 (King George VI), 1953 Florin (Queen Elizabeth II).