Aliens may have existed in our solar system long before us
By Jasper Hamill, The Sun
"A prior indigenous technological species might have arisen on ancient Earth or another body, such as a pre-greenhouse Venus or a wet Mars," he wrote.
http://nypost.com/2017/04/25/aliens-may-have-existed-in-our-solar-system-long-before-us/Two problems there -- there was no "pre-greenhouse Venus", or a "wet Mars". Mars has been nearly airless and bone dry throughout its existence. The best place to look for prehuman technological crap is right here on Earth.
Lost empires of extinct non-human species is often entertaining to contemplate:
Star Trek - The Next Generation - S 1 E 5 - The Last Outpost
http://www.dailymotion.com/video/x4oopr1Star Trek - The Next Generation - S 2 E 11 - 'Contagion' - (scene, Destruction of the Yamato)
https://www.youtube.com/watch?v=_1WtRpPG8C0