System for forming a covering, in particular a parquet floor, on an underground, wherein the system has the following: a plurality of underground laying units, which are layable on the underground and connectable to the underground for jointly covering the underground; wherein an underground laying unit has: a board-type rigid stability layer for stabilizing a surface laying unit that is attachable above the stability layer; and a connection structure, which is attached on an upper side of the underground laying unit, and which is configured for reversibly and non-destructively releasably connecting to the surface laying unit; wherein a bottom side, that is opposite to an upper side, of the underground laying unit is configured for connecting to the underground; a plurality of surface laying unit, which are provided separately from the underground laying units and are configured for covering the laid underground laying units, wherein the surface laying unit has: a wear layer, wherein the wear layer has a thickness in the range between 0,5 mm and 4 mm, and is formed as a board; a further connection structure, which is arranged directly on a bottom side of the wear layer, and which is configured for reversibly and non-destructively releasably connecting to the underground laying units; characterized in that a first lateral surface of the stability layer has a first engagement element and a second lateral surface of the stability layer has a second engagement element, which is complementary to the first engagement element, wherein the first engagement element is connectable to a corresponding second engagement element, and the second engagement element is connectable to a corresponding first engagement element of corresponding underground laying units. a plurality of underground laying units, which are layable on the underground and connectable to the underground for jointly covering the underground; wherein an underground laying unit has: a board-type rigid stability layer for stabilizing a surface laying unit that is attachable above the stability layer; and a connection structure, which is attached on an upper side of the underground laying unit, and which is configured for reversibly and non-destructively releasably connecting to the surface laying unit; a board-type rigid stability layer for stabilizing a surface laying unit that is attachable above the stability layer; and a connection structure, which is attached on an upper side of the underground laying unit, and which is configured for reversibly and non-destructively releasably connecting to the surface laying unit; wherein a bottom side, that is opposite to an upper side, of the underground laying unit is configured for connecting to the underground; a plurality of surface laying unit, which are provided separately from the underground laying units and are configured for covering the laid underground laying units, wherein the surface laying unit has: a wear layer, wherein the wear layer has a thickness in the range between 0,5 mm and 4 mm, and is formed as a board; a further connection structure, which is arranged directly on a bottom side of the wear layer, and which is configured for reversibly and non-destructively releasably connecting to the underground laying units; a wear layer, wherein the wear layer has a thickness in the range between 0,5 mm and 4 mm, and is formed as a board; a further connection structure, which is arranged directly on a bottom side of the wear layer, and which is configured for reversibly and non-destructively releasably connecting to the underground laying units; characterized in that a first lateral surface of the stability layer has a first engagement element and a second lateral surface of the stability layer has a second engagement element, which is complementary to the first engagement element, wherein the first engagement element is connectable to a corresponding second engagement element, and the second engagement element is connectable to a corresponding first engagement element of corresponding underground laying units.