Beyond the receiving zone, at each camp was a narrow, camouflaged path known as the Road to Heaven (called Himmelfahrtsstraße or der Schlauch by the SS), which led to the extermination zone consisting of gas chambers, and the burial pits, up to 10 meters deep, later replaced by cremation pyres with rails laid across the pits on concrete blocks; refuelled continuously by the Totenjuden.