The Wall of Jericho was a Pre-Pottery Neolithic A (PPNA) defensive or flood protection wall suggested to date to approximately 8000 BC. If interpreted as an "urban fortification", the Wall of Jericho is the oldest city wall discovered by archaeologists anywhere in the world. It is built of undressed stones and is located at the archaeological mound known as Tell es-Sultan, in the city of Jericho on the West Bank - Wikipedia
It seems too unrealistic that Neolithic farmers would be building walls at this point in history , to protect them against who? , hunter gatherers?