The clearest public acknowledgment of this underworld pair in Roman state religion came at the Ludi Saeculares, the Secular Games marking the passing of a saeculum, the longest span of a human life, held only a handful of times across Roman history. Their altar, the Tarentum or Ara Ditis, stood on the Campus Martius and was, according to Roman antiquarian tradition, buried after each use and only uncovered again when the next Secular Games fell due, a practice that treated the underworld deities' altar itself as belonging to a different order of time than the everyday sacred calendar, surfacing only once in a lifetime rather than annually like the altars of the Olympian gods above.
At the games themselves, sacrifices offered by night to Dis Pater and Proserpina, black victims appropriate to chthonic deities, opened a festival that otherwise turned quickly toward daytime celebration of Rome's continuity, so that the underworld pair's brief, deliberately archaic rite functioned as a kind of hinge between one generation's Rome and the next, honoring the realm that had claimed the last saeculum's dead before turning to celebrate the new one being born. No comparable rite honored Dis Pater and Proserpina at any other point in the Roman religious calendar, which is part of why historians read the underworld pair's appearance here as a deliberate, tightly bounded exception rather than an ordinary recurring cult.