I'm looking at a science fiction scenario similar to Lovecraft's At the Mountains of Madness where buildings are exposed to the elements for millions of years. I have a feeling they wouldn't be quite as intact as Lovecraft had it, so I want to try to figure out what's realistic.
As in Lovecraft, the location is a geologically stable plateau that is very dry and permanently below freezing point so no earthquakes, volcanoes or water.
The buildings are sturdy construction, reinforced concrete.
What would be left after one, ten, a hundred million years? For the purposes of the story, I don't need them to be usable, just to have enough remains for investigation by archaeologists.