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:
“He is a stranger to me but he is a most remarkable man—and I am the other one. Between us, we cover all knowledge; he knows all that can be known and I know the rest”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)