I was recently in New Grange (goole it)
It is solar aligned and the dry stack has been standing for thousands for years. The inside is still bone dry so if you get it to exist it will likely exist for human scale forever
When ya get to the big stuff, 1,000 pounds up. Just add me to the resource list. Built many adventure golfs on the "hill" caves, retaining walls and waterfalls. Natural stone not gunite. Up to 12 ton, (bout the size of a vw beetle).
A few years later, but in this newly released YouTube vid by Paul, you can see the completed moon gate that was one of the projects from the PTJ this year. Check out Paul's walk about Wheaton Labs to check out a bunch of new improvements, courtesy of the events and permaculture bootcamp peeps.
That drystack moon gate is beautiful! in principle, it is simple to build - just stack rocks on top of each other. But I bet it is no easy task stacking it just so, so that the structure stays together. Have a closer look at the elegant build here: https://www.youtube.com/watch?v=OfvPzGi21QM