Archeology and Mount Ebal

From the ESV Online Study Bible:

Mount Ebal is on the north side of Shechem (see 11:29 and note on 27:1–8). This ceremony occurs on the mountain of curse (see v. 13) to show that the law functions as a witness against Israel because of its inevitable sin.

wield no iron tool. Israel’s altars were to be of unhewn stone (Ex. 20:25).

Excavations at Mount Ebal have uncovered a worship site with a large altar (30 x 23 feet/9.1 x 7 m) constructed of unhewn stones, accessed by a gently sloping ramp. The pottery dates to the Israelite settlement (cf. Josh. 8:30–32). This perhaps is the altar that Joshua built or is built on top of Joshua’s altar.

Click here for an article, “A mysterious structure filled with ashes and burned bones”  by the man who excavated Mount Ebal

And for another, “Shechem and mount ‘ebal in the bible: is this indeed Joshua’s altar?”