The Gates of Hera are twin mountain peaks on Kobol that mark the entrance to the Tomb of Athena. In Colonial mythology, it is the point from which Athena jumped to her death in despair over the Exodus of the Thirteen Tribes of Man. The path that leads to the Gates of Hera is lined with ancient gravestones.
Compare the Pillars of Hercules.
Trivia
The Gates of Hera are actually twin peaks just north of Vancouver, where the show is filmed. They rise prominently over downtown Vancouver and are known locally as "the Lions."