“Sewer covers” started off as slabs of stone or pieces of wood allowing access to covered trenches that carried sewage. This basic design was in use from 3500 BCE through the1850s. With industrialisation sewers evolved into an underground system of pipes, grates and access points. The oldest known foundry catalog for these sewer covers dates back to 1860. Many of the London’s manhole covers used to day are made by a firm which made its first water main cover in 1856.