Pandora's Gate in God of War.
Pandora's Gate (beyond Pandora's Bridge) was the only true entrance to Pandora's Temple, and could only be opened by the Body Burner. When anyone attempted to enter the Temple, the Body Burner must first test their abilities by unleashing a group of Cyclops Desert Kings against them. Only after the Cyclops' were defeated, could the gate be opened, which lead into the Temple. It's opened by the Harpies who served the Body Burner, who then opened it when he gave them the signal.