Measuring 33.5 centimetres (13.2 in) high and weighing 1.59 kilograms (3.5 lb), it is the largest known metal bust of a Roman emperor and is considered one of the most important archaeological finds in Switzerland.

[1] Discovered by chance during an excavation of the sewers of the Cigognier sanctuary in Aventicum, the bust is kept for security at the Banque cantonale vaudoise in Lausanne; a copy is on permanent display at the Roman Museum in Avenches.

Initially identified as the emperor Antoninus Pius, the bust is more frequently considered to represent his successor, Marcus Aurelius, in his old age.

The gold bust was discovered on April 19, 1939 in Avenches by unemployed workers from Lausanne participating in an occupational program[N 1] organized by the association Pro Aventico which manages the city's ancient heritage.

They were under the direction of the cantonal archaeologist Louis Bosset, the curator of the Roman Museum of Avenches Jules Bourquin and the scientific director of the site André Rais since October 21, 1938; their mission consisted mainly in revealing the outline of the building attached to the Cigognier column.

[2] It was during the excavation of sewer number 1 of the site that a worker hit a metal object with his pickaxe; the bust was in a pipe, buried in silt and black earth, and was almost entirely covered with limestone.

Weighing about 1.6 kilograms (3.5 lb) at the time of its discovery, the bust is the largest gold find made in Switzerland, and it was immediately registered by a notary.

[14] Aventicum is considered one of the richest archaeological sites in Switzerland and has been the subject of systematic excavations since the establishment of the Pro Aventico association in 1885.

This has been attributed to the plundering of the city during an Alemanni invasion in the third century: many inhabitants, taken by surprise, did not have time to secure their belongings and hid them underground.

[23] It has not been melted either, as proven by its thinness; the bust was shaped by hammering, and its thickness varies according to the work at different points on its surface.

[21][24] A tomographic analysis conducted in 2016 shows that the craftsman began his work with the narrowest part of the bust, the neck, and ended with the torso.

A plaster copy dating from 1941, still on display at the Musée Monétaire Cantonal in Lausanne in 2006, was in a poor state of preservation and the red of the coating applied to the bust before gilding showed.

The longevity of these copies was questioned by Anne de Pury-Gysel, director of the work on the Aventicum site, because the decomposition of the busts over time created small black spots on the surface.

The chin is slightly triangular, with a very round skull and a large forehead, whereas other statues of Marcus Aurelius present a more vertical and rectangular face.

The body wears three layers of clothing, including a Roman cuirass with a Gorgon in the center and, on the left shoulder, a paludamentum originally held by a brooch, which has disappeared and must have been made of a precious stone.

[40] The facial expression of the bust is similar to that found in reliefs of the Arch of Marcus Aurelius in Rome (built in 176), as well as in series of coins issued between 170 and 180.

[42] In 1980, the French-Belgian archaeologist Jean-Charles Balty proposed a reinterpretation of the bust, arguing that it represents the 4th century AD Roman emperor Julian.

[44] Hans Jucker, a Swiss Classical Archaeologist, responded to Balty a year later by pointing out that the 'frontality' of the statue is explained by its use as the end of a staff and that the hairstyle of the bust is ultimately not similar to any known Roman emperor portrait, demonstrating local manufacture rather than a different identification.

[48] However, the context remains unclear; the American archaeologist Lee Ann Ricardi suggests that it was used as a war sign, but Aventicum is not known as a military town.

[43][49] Another possible explanation is that the bust was used in celebrations, carried on a pole as a parade head, as depicted in a mural from the Roman villa at Meikirch, in the canton of Bern.

[51] Arguments in favour of this theory include its Celtic-style headdress, the fact that sources of gold were known in Helvetia in the first century AD and the existence of two goldsmiths - a father and son - in Aventicum at the same period, as attested by a funerary stele from the site.

[51] A copy of the bust was presented to Benito Mussolini by the head of the Department of Public Education in 1941 to thank him for his donations to the Vaud Cantonal Library.

Applying the Swiss Civil Code, the court declared the bust to be an "object of public interest", allowing it to become part of the State's collections.