A manhole is a covered opening in a street or sidewalk that provides access to underground utilities, such as sewer systems, water lines, and electric cables. Typically made of metal or concrete, manholes are designed to be strong enough to support the weight of vehicles and pedestrians. They often have a round shape, which helps prevent them from falling into the hole. Manholes are essential for maintenance and repairs, allowing workers to enter underground systems safely. The covers are usually marked with symbols or letters indicating the type of utility they access, helping to identify the services below.