Hollow stones

I have in my travels found very large stones that are hollow big enough to live in like a house.  I came across one of  these by moving some brush at the top side and crawled under the stone to find it hollow. Then there is one huge stone that is hollow with no entry it feels like it is going to collapse under my weight and when tapped it rings like a drum. In one of my videos there is a stone column that has possibly been broken in half and which are laying one on top of the other. The surrounding area does not have stones like them, weighing in at around 40 tons each. Then there is a wall made with out mortar which I will examine in some detail in the coming months. These are like the close fitting stones of the Incas. I will photograph these on my next visit as last time I did not have my camera with me. Who would have thought I would have become an archaeologist in my later years.