Diablo 3 Senior Level Designer Matthew Berger has revisited his Greyhollow Island “Lightning Talk” which he did at BlizzCon this year. In the video Matthew talks about the new zone and how it evolved into what you see today on the 2.4.0 PTR.
If you didn’t attend BlizzCon then this is worth a watch because the video shows early iterations of the zone design. He also discusses events that didn’t make the final version and the Ancient City which was completed and then removed.