… I would not sponsor a street called ’11th of spetember’ as this invokes slightly too much images of planes crashing into buildings in my head. Areolineas Argentinas (the argentininan flag carrier) seems to think otherwise as this street sign form the Buenos Aires neighbourhood of Belgrano illustrates:

The street in question seems to have this name since before the 9/11 2004 but (at least to me) it is unclear what the name referrs to. One possibility would be that the name is given in commemoration of the 1973 military coup in neigbouring Chile (this is a slightly strange event to name a street after in itself but given Argentinias political history not inconcievable). The only genuine Argentinian event mentioned in the wikipedia entry for 11 september is the death of the Argentinian statesman Domingo Faustino Sarmiento who died on the 11th of September 1888.