Ah, DaveofCali... I was just about to email you after looking up
www.wtc3d.com on the Internet Archive. I was a fan of yours for that very reason; that you could actually walk through a fairly detailed recreation. Actually, my computer had a hard time handling it back then, but I put up with my computer's frame rates because what I did see was very much worth it.
It's a shame the domain's down, cause I'd love trying it out on my more up-to-date computer. (Got a Radeon X800 Pro for Half Life 2 when it came out in 2004... which is nothing now!
Can't someone create a "game" environment, keeping the detail, while still being able to walk through smoothly?