"I was raised as a Quaker," he says, "and they always talked about going inside to greet the light. I was interested in that. Not only in the visible

but in the light seen with the eyes closed, the light and color in dreams."

I'm reading about Roden Crater in Arizona, trying to find out if it's finally open to the public. Absolutely fascinating story. http://www.phoenixnewtimes.com/2008-09-04/calendar/maya-lin-and-james-turrell-art-from-earth-and-sky
Click on the old article below the photo of the crater. Also, Google has a satellite view and there's an old NYT article describing how hard it is to get an invite. Best I can tell it's still not open.