Moving back as far as the Roman times, in ancient Rome Man has started using stone to protect drain covers.

The layman term for drain cover (grate) is manhole cover. Say “manhole cover” and pictures of spies/heros 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 cover s or grates as we would prefer to call them) have already been invented out from the necessity to prevent people from falling into underground sewage and also to prevent large objects from entering the drains which cause choking which eventually may cause flooding.
Fast forward to the present day, the sewage system is still in use under all cities worldwide. Instead of the crude stone manhole covers the Romans use in the ancient days, today we have special steel reinforced stone gratings that serve the thousand year old function of covering the inlets of our sewage system.
Far more than a cover, check out Jonite’s range of drain covers (drain gratings) here: