Last night at Bible study we were talking about the book of Joshua, and we discussed the ancient walls found under Tel es-Sultan (the mound of ancient Jericho) during the excavation. Here's a picture of the ancient walls down toward the bottom of this picture.
From my Bible software: "Recent digs at the Tel es-Sultan have revealed that the walls in a specific section do indeed date back to the time of Joshua. It is difficult to find the original walls due to the large number of times Jericho has been rebuilt (at least 23 times over a period of more than 8,000 years). After Joshua conquered the city and dedicated it to the Lord, he pronounced a curse on anyone who attempted to rebuild it (Jos 6:26). This curse was fulfilled during the reign of King Ahab (1Ki 16:34)."