Buenos Aires ( / ˌ b w eɪ nə s ˈər iː z / ko /-- ˈaɪrɪ s / ; Spanish pronunciation: [ˈbwenos ˈajɾes] ( </img> ), a hukumance birnin Buenos Aires mai cin gashin kansa ( Spanish: ), shine babban birni kuma babban birni na Argentina. Birnin yana yammacin gabar tekun Río de la Plata, a gabar tekun Kudu maso Gabashin Amurka. Ana iya fassara "Buenos Aires" a matsayin "iska mai kyau" ko "iska mai kyau", amma tsohuwar ita ce ma'anar da waɗanda suka kafa a karni na 16 suka yi, ta hanyar amfani da ainihin sunan "Real de Nuestra Señora Santa María del Buen Ayre". Mai suna bayan Madonna na Bonaria a Sardinia, Italiya. An rarraba Buenos Aires a matsayin birni na duniya na alpha, bisa ga Globalization da Cibiyar Binciken Biranen Duniya (GaWC) 2020.
Birnin Buenos Aires ba ya cikin lardin Buenos Aires ko babban birnin lardin; a maimakon haka, gunduma ce mai cin gashin kanta. A cikin 1880, bayan shekaru da yawa na rikice-rikicen siyasa, Buenos Aires ya zama tarayya kuma an cire shi daga lardin Buenos Aires. An fadada iyakokin birnin har zuwa garuruwan Belgrano da Flores; dukkansu yanzu unguwannin birnin ne. Canjin tsarin mulki na 1994 ya ba wa birni ikon cin gashin kansa, don haka sunan shi na gari na Buenos Aires mai cin gashin kansa. Al'ummar kasar sun fara zaben shugaban gwamnati a shekarar 1996; a baya, Shugaban kasar Argentina ya nada magajin gari kai tsaye.