For centuries this was two plazas, not one. A colonnade called the Recova, completed in 1804, split the space into the Plaza de la Victoria on one side and, toward the river fort, the Plaza del Fuerte on the other. In 1811 the May Pyramid rose in the western half to mark the first anniversary of independence, becoming the city's first national monument. Then in 1883 Mayor Torcuato de Alvear had the Recova torn down, fusing the halves into the single great square inaugurated the following year as the Plaza de Mayo, named for the May Revolution of 1810. Around it gathered the institutions of a capital: the colonial Cabildo, the Metropolitan Cathedral, the Banco de la Nación, the city hall, and, facing the river, the pink presidential palace, the Casa Rosada.

The Casa Rosada, seat of Argentina's president, gives the plaza its colour and its drama. From its balcony, leaders have spoken to oceans of people filling the square below, none more famously than Juan and Eva Perón, whose rallies drew vast working-class crowds in the 1940s and 50s. The square became the natural amphitheatre of Argentine politics, the place where popular power was both summoned and displayed. It could also turn deadly. On 16 June 1955, military aircraft opposed to Perón bombed the plaza during a rally, killing 364 people in one of the darkest single days the square has witnessed, an attack on a crowd of civilians at the symbolic centre of their own capital.

The square's most enduring image is also its quietest. Beginning in 1977, at the height of the military dictatorship, mothers of the desaparecidos, the disappeared, began gathering here to demand their children back. These were people, often young, who had been seized by the state, secretly detained, tortured, and murdered for holding left-wing views or merely for knowing someone who did, then made to vanish without a body or a grave. Forbidden to stand still, the mothers walked in a slow circle around the May Pyramid, wearing white headscarves to recognize one another. The Madres de Plaza de Mayo turned their grief into the regime's most visible accusation, using the symbolic weight of this square to force the world to look. They have walked their circle every Thursday for decades. Many still do.

The plaza never stopped being a place where the nation gathers. Crowds filled it on 2 April 1982 to cheer the seizure of the Falkland Islands, and the same ground heard the silence when that war was lost. During the economic collapse of December 2001, protests around the square turned violent, and five people were killed by police in the riots that brought down a government. Today the Plaza de Mayo is at once a tourist landmark and a working political space, ringed by its centuries of history: the Cabildo and Cathedral, the equestrian statue of General Manuel Belgrano, the financial district the Porteños call la City just beyond. To stand at its centre is to stand where Argentina has come, again and again, to decide who it wants to be.