On http://twhl.co.za/mapvault_map.php?id=3657 you can download a Half-Life 2 level of the famous Kaufmann House by F.L. Wright. This is currently one of the best uses of realtime technology for architectural design. The whole house, including the environment is explorable in realtime, including sound, light and texturing. There is even one of the (sci-fi) Half-Life 2 cars parked outside, should you want to take a ride.