Covers for structures, for example drainage channels or the like, which can be installed into a floor are known, said covers comprising a surface (11) which can be accessed and driven over and which comprises a flat structure (13) on a first lower plane and elevations (14) with top surfaces lying above the flat structure (13) on a second higher plane. The aim of the invention is to improve the non-slip properties and to achieve a self-cleaning effect. This is achieved in that the top surfaces (15) have an anti-slip surface structure which comprises a plurality of individual elevations. The ratio of the air volume below the individual elevations (16) to the volume of the individual elevations (16) is Vv/Vm=(0.01 to 0.5)/(0.001 to 0.05).