When were the walls of Jericho built?

Archaeologists date the building of the walls of Jericho to around 8,000 BCE (10,000 years ago)! The settlement first started showing occupation around 9,000 BCE, so about 1000 years went by before the wall was built. Contrary to the 70-foot height mentioned in the Book of Joshua, the walls actually reached a height of 13 feet with 28-foot watchtowers at critical points.

By the time the wall was built, there were an estimated 2,000 to 3,000 inhabitants of Jericho. So the wall was built to both protect the town and more importantly the water supply.

https://www.britannica.com/place/Jericho-West-Bank