The building was raised for the Caja del Seguro Obrero Obligatorio, the compulsory workers' insurance fund created in 1924 - an institution born of Chile's early experiments in social welfare, in a decade when the country was beginning to write the rights of laborers into law. The architect Ricardo Gonzalez Cortes drew on two of the era's most forward-looking currents: the structural boldness of the Chicago school, which had taught the world how to build tall, and the geometric elegance of Art Deco, then sweeping fashionable cities everywhere. Construction ran from 1928 to 1931, and when the tower topped out at twelve stories it surpassed the nearby Edificio Ariztia as the tallest office building in the country. For a young agency dedicated to the wellbeing of working people, the building was a statement of permanence and purpose, planted at the very heart of the capital, where the government and the nation could not help but see it.

On 5 September 1938, Chile was weeks from a presidential election and simmering with political tension. A group of young men from the National Socialist Movement of Chile - the Nacistas, modeled on European fascism and hoping to clear a path back to power for the former president Carlos Ibanez del Campo - attempted to seize power. A contingent occupied the Seguro Obrero Building, just steps from La Moneda, while another group seized a nearby university building. A gun battle erupted between the occupiers and the Carabineros, Chile's national police. Outgunned and surrounded, the young men inside the tower surrendered. They had been promised they would not be harmed.

The promise was broken. Inside the building, the police shot the men after they had given themselves up. Fifty-nine were killed. Of the roughly sixty-three who had taken part in the failed uprising, only a handful walked out alive. The dead were overwhelmingly young, and the killing was not combat but execution - prisoners shot after laying down their arms, allegedly on orders that reached to the office of President Arturo Alessandri himself. Whatever one makes of the politics that brought these men to the building, what happened to them after they surrendered was a massacre, and Chileans named it plainly: the Matanza del Seguro Obrero. A classic of Chilean literature, 'Los asesinados del Seguro Obrero,' would later be written to keep the memory of that afternoon alive.

The bloodshed did not secure power for anyone - it transformed the country's mood instead. Public revulsion at the killings swung sympathy toward the left, and weeks later the Popular Front candidate Pedro Aguirre Cerda won the presidency, an outcome the massacre helped decide. The building, meanwhile, kept working. Since November 1989 it has housed the Ministry of Justice, an institution whose very name sits uneasily with what the walls once witnessed. Today the elegant Deco tower stands as it has for nearly a century, beautiful and unassuming, while the corner it anchors carries a memory that Chile has never quite let go.