Charleston is one of the few cities in North America to ever have been a walled city. In the early 1700’s, the wall protected the residents from everything from pirates to the Spaniards and French. While the wall has been mapped, there are only a few spots where you can actually see its remnants. The brick line here, across the cobbles of North Adgers Wharf, represents where the wall crossed at that point — and if you dig down you will find it (but do not do that without permission and proper archaeological processes!)