Portunus
In Roman mythology, Portunus (also called Portunes ) was the god of the doors and the keys, guard of the corn warehouses of the edges of the the Tiber. Its attribute is a key. Sometimes one associates it to the Greek god Mélicerte or Palaemon and thus inherits also the title of god of the ports and the navigators.
Its temple (also called Fortuna temple Virile ) is located close to the Forum Boarium. The festivals with its honor are the Portunalia , celebrated on August 17th on the occasion of which one threw keys in fire to protect itself from the bad luck.