Argentina km 0, Kilometer zero monolith in Balvanera, Buenos Aires, Argentina

Argentina km 0 is a rough-hewn rectangular stone monolith on a white concrete base, standing on reddish gravel west of Plaza Mariano Moreno, on Virrey Cevallos between Rivadavia and Hipólito Yrigoyen. Its front face is engraved "VIRGEN DE LUJAN" and "PATRONA DE LAS RUTAS NACIONALES" above a tile plaque of the Virgin; the north face carries the image of Nuestra Señora de Luján, the south a relief map of Argentina, the west plaques honouring San Martín and the east a plaque with the 1944 decree date.

The monolith was made by the sculptor brothers Máximo and José Fioravanti and inaugurated on 5 October 1935, with President Agustín P. Justo and Public Works Minister Manuel Ramón Alvarado present. It first stood at the sharp angle of Plaza Lorea where Avenida de Mayo meets Rivadavia. A decree of 18 May 1944 moved it a few metres to its present spot west of Plaza Mariano Moreno, on Virrey Cevallos between Rivadavia and Hipólito Yrigoyen.

The north face carries an image of Our Lady of Luján, patron saint of the national road network, while the south face shows a relief map of Argentina. Plaques on the west face honour San Martín, and the east face bears a plaque with the date of the 1944 relocation decree. The monument's role echoes the Miliarium Aureum, the column Caesar Augustus raised to mark the start of Rome's roads.

The monolith stands west of Plaza Mariano Moreno, on Virrey Cevallos between Rivadavia and Hipólito Yrigoyen, beside Plaza del Congreso. It is a short walk from the Congreso and Avenida de Mayo area, so it can be seen on foot while crossing between the two squares.

The monolith's four faces carry different elements: a relief map of Argentina on the south face, plaques honouring San Martín on the west, and the date of the 1944 relocation decree on the east. The custom of marking a road network's origin this way traces back to Emperor Caesar Augustus, who set up the Miliarium Aureum in Rome.