“the sacred precinct.” Although many versions say “sanctuary,” the Hebrew word can refer to a holy place, which Shechem surely was, going back to the time of Abraham. The NIV reads “holy place,” while the TNK reads “sacred precinct.” There is no evidence that the Tabernacle was moved from Shiloh (Josh. 18:1) to Shechem for this event.
“took a large stone and set it up there.” There is still a huge stone (although some of it has been broken off) in an ancient cultic site in Shechem, that seems to have ruins associated with it, or near it, that date from this time or earlier. There is no way to tell for sure, but that could well be the very stone that Joshua had set up. This standing-stone that Joshua set up was to be a memorial and a witness of the covenant that he made with Israel concerning the worship of Yahweh.
[For more on standing-stones, see commentary on Gen. 28:18.]