HellMap
I tried tagging it what I think it should be. But there are so many options and variants on Wiki and I haven't really tagged such things before, so I have no idea if this is right.

One thing is that I think these should be buildings - these seem to be old support pillars of the actual lock gate structure, which is completely gone. [1]

[1] https://www.facebook.com/1401426159912286/posts/3511131285608419/