The aviary can be as elaborate or as simple as you'd like, as I said earlier a ten by ten foot aviary is big enough for a pair of golden pheasants. These birds come from densely overgrown forests so I suggest that you heavily plant the aviary with plenty of shrubs. If you want an authentic look, you can even plant hardy varieties of bamboo. The plumage of the males will fade if they are not provided with shade, so keep that in mind and be sure to provide plenty of cover to prevent that from happening. I wouldn't plant any thin leafed plants or too many grasses, they'll end up just being a very expensive snack, instead choose non poisonous thick leaved shrubs. Branches and rocks are also appreciated, they can be perched on to stay off the ground at night and provide some entertainment during the day. Out of all the pheasants I believe golden pheasants perfer perch more so others, my one male will sit for hours on an old tree branch in the center of our aviary. It's a pleasure to watch him out the window.