Constitución is a barrio or neighborhood of Buenos Aires, Argentina, approximately two kilometers south of downtown.

Work began in 1864 on the Buenos Aires Great Southern Railway led the opening of a station at the market and with it, the rapid growth of the area as an immigrants' quarter.

A non-profit clinic opened by the Anglican Reverend Barton Lodge in 1844 became the British Hospital in 1887 (still the borough's largest).

The neighborhood was subsequently home to Hipólito Yrigoyen, a co-founder of the centrist Radical Civic Union in 1891 who tirelessly campaigned for and, in 1912, won the right to universal (male) suffrage in Argentina and the secret ballot.

The mayor appointed in 1976 by Argentina's last dictatorship, Osvaldo Cacciatore, had plans drawn up for eight freeways within the city proper, three of which were finished.