Actually... I wonder about that. 8000 years... certain types of concrete might last that, depending on the environment (erosion regime, for he most part). Hardened, buried structures like subsurface bunkers and whatnot should, theoretically at least, survive in part, because they're underground (i.e. minimal destructive forces, although they might theoretically corrode due to groundwater/humic acid, and fill up... although not neccesarily, there are lots of subsurface cavities that don't fill up.
Thick beams of materials like aluminium might survive, given the oxide coating, although again, environmental factors play a part. Then there's stuff like the non-biodegradeable plastics - not building materials, I guess, but they'd exist as evidence of our society...
Remember, even relatively delicate structures like papyrus have survived from Ancient Egypt, and a lot of good archaeological information comes out of places like Catal Huyuk (sp.?). I suspect that the Ancient homeworld could yet yield up some cool information, and potentially technology, but since nobody's ever excavated a technological society, there's really no way to know.