Moving back as far as the Roman times, in ancient Rome Man has started using stone to cover drain covers.
overflow grating for drain cover (grate) is manhole cover. Say "manhole cover" and pictures of spies/ stormwater drain covers using the underground sewage system popping out of manhole cover in Hollywood films appear.
Historically since that time Man invented the sewage system since the Roman Times to drain water and urban waste away for sanitation purposes, manhole covers (drain covers or grates as we would prefer to call them) have been invented out of the necessity to stop people from falling into underground sewage as well as to prevent large objects from entering the drains which cause choking which eventually can cause flooding.
Fast forward to the present day, the sewage system is still being used under all cities around the world. Rather than the crude stone manhole covers the Romans use in the ancient days, we now have special steel reinforced stone gratings that provide the thousand year old function of covering the inlets of our sewage system.
More than simply a cover, check out Jonite's range of drain covers (drain gratings) here: http://www.jonite.us/products/creative-grates