Going back as far as the Roman times, in ancient Rome Man has started using stone to cover drain cov

The layman term for drain cover (grate) is manhole cover. Say "manhole cover" and images of spies/heros making use of the underground sewage system popping out of manhole cover in http://www.jonite.us/products/usa-decorative-grates appear.

Historically since that time Man invented the sewage system since the Roman Times to drain http://www.jonite.us/products/tree-grates and urban waste away for sanitation purposes, manhole covers (drain covers or grates as we 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 worldwide. As opposed to 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: http://www.jonite.us/products/creative-grates