Cain settles down. Although it is still spiritually true, his gloomy premonitions that he will be a fugitive and wanderer do not come true. He may continue his (settled) life, unlike the keeper of sheep. It is unknown where Nod was. The Flood that wiped out the garden of Eden also wiped out this land. The east side of the Garden (apparently the entrance, Genesis 3:24) had been sealed off by God. Cain passes by the menacing cherubim and even takes up residence there. Perhaps with a vague hope of restoration of the former perfection? Perhaps retaking paradise from God from his city/fortress?
16 Then Cain went away from the presence of the LORD and settled in the land of Nod, east of Eden.