Manhole cover

Common card · No. 236142

A manhole cover is a removable plate forming the lid over the opening of a manhole, an opening large enough for a person to pass through. It is used as an access point for an underground vault or pipe. It is designed to prevent anyone or anything from falling in, and to keep out unauthorized persons and material. Manhole covers date back at least to the era of ancient Rome, which had sewer grates made from stone.

Read on Wikipedia · Image Bart Everson, CC BY 2.0