I finished A Green and Ancient Light. It was a lovely story about the loss of childhood innocence. I definitely recommend it. In the Acknowledgments he explains that the inspiration for the sacred woods in the story is the real-life Park of the Monsters (Parco dei Mostri in Italian). It was built by Pier Francesco Orsini, called Vicino, to cope with his grief after his wife died. Fascinating!
https://en.m.wikipedia.org/wiki/Gardens_of_Bomarzo