A manhole cover is a removable plate forming the lid over the opening of a manhole, to prevent anyone or anything from falling in, and to keep out unauthorized persons and material.
They date back at least to the era of ancient Rome, which had sewer grates made from stone.
Read more about Manhole Cover: Description, Circular Shape, Manhole Covers and Race Cars, Propelled Into Space, Other Uses, Gallery
Famous quotes containing the word cover:
“There is reason in the distinction of civil and uncivil. The manners are sometimes so rough a rind that we doubt whether they cover any core or sap-wood at all.”
—Henry David Thoreau (1817–1862)