Siddhashila is an area in Jain cosmology at the apex of the universe, which is where the Jains believe people who have become arihants and tirthankaras go after they die and attain moksha.
In Jain cosmology, Siddhashila is the ultimate destination for those who have attained enlightenment as arhats or tirthankaras. It's considered the apex of the universe, a place where they reside after death.