The modern plaza took form in 1884 when the colonnade separating the Plaza de la Victoria and the Plaza del Fuerte was demolished. Its origins, however, can be traced back to Juan de Garay's foundation of Buenos Aires itself, in 1580. Newly arrived to the dusty riverbank settlement, Jesuit clergymen in 1608 secured a title to much of the lot, on which Garay's earlier plans for a central plaza had been abandoned. In 1661, the local governor purchased the eastern half for inclusion into the grounds of the city's new fort; this section soon became the Plaza de Armas Following over a century of overuse and neglect, the local colonial government attempted to give a semblance of order to the plaza by having a colonnade built across it from north to south. Completed in 1804, the Romanesque structure became the plaza's market and the lot to the west of the colonnade became the Plaza de la Victoria. The area continued divided between these two plazas until 1883 and with only minor changes in landscaping, chief among them the 1811 addition of the May Pyramid, a monument put up to commemorate the newly independent "Provinces of the Rio de la Plata". That year, however, Mayor Torcuato de Alvear ordered the space modernized, resulting in the resulting in the colonnade's demolition and the creation of the modern ''Plaza de Mayo.
On October 17, 1945, mass demonstrations in the Plaza de Mayo organized by the CGTtrade union federation forced the release from prison of Juan Domingo Perón, who would later become President of Argentina; during his tenure, the Peronist movement gathered every October 17 in the Plaza de Mayo to show their support for their leader. Many other presidents, both democratic and military, have also saluted people in the Plaza from the Casa Rosada's balcony.. In an attempt to overthrow President Perón, the plaza was bombed during one of the populist leader's many rallies there on 16 June 1955, killing 364.
1970s - present
Years later, in 1974, Perón, then president for the third time, expelled from the Plaza members of the Montoneros, an armed organization on the far left that had contributed to the aging leader's return from exile the previous year and had since demanded influence within the national government. Perón's final appearance at the plaza, on 12 June, was marked by an acrimonious break with the far left, leading to two years of violence and repression and, ultimately, a coup d'état. Crowds gathered once again on April 2, 1982, and several occasions thereafter to hail de facto President Leopoldo Galtieri for Argentina's invasion of the Falkland Islands, which launched the Falklands War. The plaza, since 1977, is where the Mothers of the Plaza de Mayo have congregated with signs and pictures of desaparecidos, their children, who were subject to forced disappearance by the Argentine military in the Dirty War, during the National Reorganization Process. People perceived to be supportive of subversive activities would be illegally detained, subject to abuse and torture, and finally murdered in secret. The Mothers of the Plaza de Mayo took advantage of the symbolic importance of the Plaza to open the public's eyes to what the military regime was doing. Protests had continued on taking place, with the major last one being during the December 2001 riots when five protesters were killed and several others injured by police as they rioted around the Plaza de Mayo.
