What's Gehenna?

Gehenna is a place in the Old Testament where evil things happened, especially with certain kings like Manasseh. It's an eschatological realm that will be parallel to the new heavens and the new earth as pictured in Revelation. We see some key parallels between the two conceptually in the New Testament. And interestingly, there's no one in Gehenna right now, you know, no souls or resurrected bodies.