Batroun is one of the world's oldest cities. Located along the Mediterranean coast in northern Lebanon, this city is known for its ancient castles and churches, quality citrus fruits, and beaches and modern nightlife. Batroun was a Phoenician metropolis that was established more than three millennia ago. The remnants of an ancient sea wall, built by the Phoenicians to protect against tidal waves, still stands along the coastline. This is not the longest or most-intact wall on our list, but it is certainly the oldest.