The cast-iron manhole covers, mostly circular, protect water, electrical and sewer lines while allowing access for workers from HOFOR. Most of the covers show geometric designs. In the street one ...

Round shapes are easier to manufacture than square or rectangular shapes, and because manhole covers are heavy, being round makes them easier to move from place to place (just roll them!).

Our contact at the NYC Department of Environmental Protection says, “The principal reason that manhole covers are round is so they won’t fall into the manhole.” Each manhole cover sits on a ...

Calgarians will soon be walking, cycling and driving over much fancier manhole covers. The city is installing new circular cast iron slabs that illustrate the various liquids washing through more ...

Manhole covers are usually round. Most people probably don't spend their days thinking about why that is. But there's actually a cool geometry reason behind the design: Circle-shaped things can't ...

Circular manhole covers – designed to be slightly bigger than the lip that holds them in place – cannot fall down the manhole, no matter which way you turn them.