The question is why are American manholes round. You can walk quite a way in Britain before you see a circular manhole cover. Domestic drain covers are almost

The question is why are American manholes round. You can walk quite a way in Britain before you see a circular manhole cover. Domestic drain covers are almost always rectangular galvanized steel, and aren't actually that heavy, so dropping one doesn't happen that often. Digging and constructing a rectangular inspection pit is much easier than a circular one.