Something ocurred to me some time back. Unbelievers will be cast into the lake of fire after the Great White Throne judgment. In biblical times, judgments were handed out at the gates of the city. I have speculated (and I cannot prove this) that Great White Throne judgment might take place at the gate of the New Jerusalem. People will be able too see what could havd been theirs if they had only believed. To have that be your last memory before being cast into the lake of fire would make it all the more sorrowful.
That is an amazing thought!