Lead seals with tetrarchic busts from the imperial palace in Sirmium

In the course of archaeological excavations of the north section of the imperial palace in Sirmium (locality 85), conducted in 2015, as many as 39 lead seals were found to the south of column IV of the polygonal structure encountered in 2014. Nine specimens of imperial seals with a representation of four busts, i.e. images of the tetrarchs, are particularly interesting in this group. These seals appear in three iconographic variants (a-c) depending on whether the four busts are positioned in two rows or in a single row and whether they are of identical size. The discovery of imperial lead seals with the busts of tetrarchs bears witness to the importance of Sirmium at the time of the tetrarchy, not only as an army base for Diocletian?s wars against the Sarmatians, but also as a commercial centre where the deliveries of various products also arrived. They were, among other things, intended for building and decorating the polygonal structure used for celebrating the imperial cult.