Wikipedia:Selected anniversaries/April 21
April 21: Mawlid in Sunni Islam (2005)
- 753 BC - Romulus and Remus founded Rome, according to the calculations by Varro Reatinus.
- 1918 - World War I: "The Red Baron", a flying ace of the German Luftstreitkräfte, was shot down and killed in France.
- 1960 - Brasília, a planned city based on principles of Le Corbusier, was officially inaugurated as the capital of Brazil.
- 1970 - The Hutt River Province "seceded" from Australia.
- 1985 - Racing driver Ayrton Senna won the first of his 41 Formula One championship races at the Portuguese Grand Prix in Estoril, Portugal.