Beginning in the reign of Augustus or Tiberius, corpses of criminals condemned and executed by the state were exposed on the Scalae Gemoniae, a flight of stairs located in the northern corner of the Forum Romanum. As one modern commentator has observed, the ritual of execution in which these stairs played a critical role reflected more generally the suppression of popular participation in the judicial processes that accompanied the last century of the Republic and the emergence of the Principate. As has long been noted, however, the Stairs were also the site of well-attested instances of collective violence, in particular protests during Cn. Calpurnius Piso's trial in the senate in AD 20, violence surrounding the fall of Sejanus in AD 31, and the popular violence and warfare of AD 69.