There are times I almost regret exploring Second Life. The talent and intellect demonstrated by so many of the residents can make me feel really really inadequate.
My friend Cyberloom was one of the many who blogged about their installation at Burning Life 2008 - this creation takes many of the techniques utilized there and expands and refines them in a wonderful way.
I don't know how to describe it in a manner that makes sense but, in addition to the beauty and wonder of the build, you will be delighted by its collapse and seemingly organic reconstruction. Fly up to 100m and just watch for a while before you explore (and be careful when you're on the ground, things might land on you).
Luckily this is one of those occasions where you don't have to just take my word for the beauty of an inworld build. The brilliant machinimatographer Toxic Menges has created a piece which should convince you to visit. :)