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:
“Every man alone is sincere. At the entrance of a second person, hypocrisy begins. We parry and fend the approach of our fellow-man by compliments, by gossip, by amusements, by affairs. We cover up our thought from him under a hundred folds.”
—Ralph Waldo Emerson (1803–1882)