According to 1 Chronicles 10:10, where did the Philistines fasten King Saul's head?

Answer: In the temple of Dagon

The Philistines put Saul's armor in the temple of their gods and fastened his head in the temple of Dagon.

“They put his armor in the temple of their gods and hung his head in the temple of Dagon.”— 1 Chronicles 10:10 (BSB)