3 greatest game environments ever

My favourite 3 are probably Racoon City, The Halo and Hong Kong from Shenmue II.

Phendrana Drifts. But I would say all of Tallon IV.

The entire envoirement of Stalker - Shadow Of Chernoybl is unrivaled in my opinion. The Capital Wasteland felt like a plastic and synthetic experience in comparison. Also City 17, Rapture, and the Core level from Crysis were pretty special. Tallon IV is probably my fondest memory though. Leaving the ship, greeted by possibly the greatest soundtrack ever. Looking around at this superbly crafted world, with rain dropping upon your visor... Mesmerizing. :o

Tallon IV soundtrack.

The Chernobyl area in Stalker

The city of Mirror's Edge

Renaissance Italy in AC2

SotC

In no particular order: Temeria from The Witcher, the surroundings of the Chernobyl nuclear reactor from S.T.A.L.K.E.R, the Galaxy from Mass Effect and City 17 and its surroundings.

The Mansion from Resident Evil is my favorite, with Hyrule and the jungle from Metal Gear Solid 3 rounding out the top three.

The Capital Wasteland, Shadow Moses, Ferelden, Ishimura, and many, many more.