Myself, my husband and my best friend were sitting on her deck that looks out towards lake travis talking and listening to music. i saw very bright white circular lights appear through the trees coming from the west. their house sits a top one of the highest elevation points in austin on 18 acres of land. at first i thought the lights were a plane or helicopter as there is a small airport near her home. i continued our conversation and looked up to see that the lights had cleared the trees and were now directly above our heads by 500 ft or so. i told everyone to look up and said what is that?! it was a triangle shape, you could see the outline that it was one giant craft. it looked to be the size of half a football field. there was no sound coming from it. it cruiser very very slowly over us and we watched it cruise over the valley below, towards lake travis and then disappeared from our view past the horizon. the entire event lasted around 8 minutes.