- 02-February-1536 : Spaniard Pedro de Mendoza founds Buenos Aires, Argentina.
- 05-July-1807 : A disastrous British attack is mounted against Buenos Aires during the second failed invasion of the Rio de la Plata.
- 10-May-1810 : Revolutionaries occupy Buenos Aires' town hall.
- 25-May-1810 : May Revolution: Armed citizens of Buenos Aires expel the Viceroy from Spain and establish a provincial government for Argentina.
- 23-July-1881 : The 1881 Border Treaty between Chile and Argentina is signed in Buenos Aires.
- 31-March-1892 : The world's first fingerprinting bureau is formally opened by the Buenos Aires Chief of Police; it had been operating unofficially since the previous year.
- 25-May-1910 : In the city of Buenos Aires the centenary of the 25th May Revolution is celebrated .
- 23-May-1928 : A bomb attack against the Italian consulate in Buenos Aires kills 22 and injures 43.
- 11-May-1960 : In Buenos Aires, 4 Mossad agents abduct fugitive Nazi Adolf Eichmann, who was using the alias "Ricardo Klement".
- 23-June-1968 : A football stampede in Buenos Aires leaves 74 dead and 150 injured.