One area that appears in Diablo 4 but in nametag only is The Lost City of Ureh.
This place has never appeared in a Diablo game, however, it was intended to be a location in Diablo 3 and made a fleeting appearance in that game's announcement video. [1] It has only appeared in the Diablo novel The Kingdom of Shadow (Buy US - UK). It hasn't featured in Diablo 4 but we have been within spitting distance of it and in fact, the steps to it are merely blocked.
For now. It may well not feature in Vessel of Hatred but it's opening up at some point.
