Hmmm... Could lead to some Oort cloud xeno-archaeology.
I poked around on Wikipedia for the last post, looking up something I dimly remembered - and found a comet with a 7.1 million year orbital period and an aphelion of 73,000 AU - 1.15 light-years!
I doubt it´s really feasible to search a cubic light-year or more around a star for a relatively small object that has a rather small chance of being there to begin with. I figure if such objects are found at all, it´s because their orbits takes them within a couple of AU of the star.
I wonder what will happen to remains and structures underground on Luna-like worlds. In a deep cave, away from micrometeorites and most radiation...
Could be relatively intact... or at least as intact as it was when abandoned. Especially if it was breached - deliberately or by an attack or accident - and is thus under vacuum inside.
Although... after 65 million years, I assume all atmosphere would have leaked out of an otherwise intact structure, too.
Either way, nothing would work any more, but structural elements and inert chunks of machinery would be a fairly impressive find from that long ago...