The Portunalia was celebrated on August 17 to honor Portunus, Roman deity of keys, doors, livestock, and harbors. Originally associated with protecting doorways and facilitating safe passage, his worship expanded to include ports and maritime transitions. Rituals occurred at the Pons Aemilius bridge, and keys were ceremonially cast into fires as offerings. In poetry, Portunalia symbolizes thresholds, protection during transitions, and the sacred nature of boundaries between spaces and states, appearing in works that explore journeys, transformations, and the Roman conception of divine guardianship over passages and portals.

Portunalia on August 17 honored Portunus, god protecting keys, doors, and harbors. The festival's emphasis on portals and transitions reflects Roman religious attention to liminal spaces and their divine guardians. Understanding Portunalia helps illuminate Roman beliefs about boundaries, thresholds, and the protection of passages. The harbor association connects Portunus to commerce and maritime activity, demonstrating how Romans extended doorway protection metaphorically to harbor entrances.