Linienwall is an outer wall of fortification, which later was made way for Vienna Beltway. The Beltway, similar to Vienna Ring Road, contains roadway infrastructure for automobiles and trams. During Red Vienna movement, Social Democrats implemented Gemeindebauten (Municipality buildings), which usually provide low-cost public social housing. Many of the housing projects became culturally and architecturally significant; i.e. Karl-Marx Hof, which is evidenced on the Beltway.