Sorita d'Este

“The Temple of Hekate at Lagina, Caria, Anatolia was the last major temple built during the Hellenistic period. The temple was constructed on the site of an older settlement, which may have included an earlier temple. Lagina is the largest known temple which was dedicated entirely to Hekate and is famous for being the site of a key-bearing procession. In this procession, a key was carried by a young girl along the Sacred Way, an 11km road which connected the temple at Lagina to the nearby city of Stratonicea. Unfortunately, we don’t have reliable information on the purpose of the ceremony. Johnston writes that: "None of our sources explain what it was supposed to accomplish, but if it took its name from a key that was carried, then that key must have been of central importance - it must have been used to lock or unlock something significant." [89] Johnston further explains that although we don’t know what the key opened, the number of inscriptions naming the festival indicates that it was a significant festival. We can speculate that it was the key to the city, the key to the temple at Lagina, or the key to another (unknown) precinct. Considering Hekate’s ability to traverse between the worlds of the living and the dead, it is conceivable that the key opened the way to some form of ritual katabasis. At Lagina, the goddess Hekate was given the epithet Kleidouchos (key-bearer), so it is also possible that the young girl who carried the keys in the procession represented the goddess in the ceremony.”
― Sorita d'Este, Circle for Hekate - Volume I: History & Mythology