By epitaxial growth of Fe on a vicinal W(110) substrate, densely spaced and continuous monolayer stripes of Fe(110) were prepared, directed along [001]. They exhibit a sharp phase transition to ferromagnetic order, free from relaxations. The magnetic easy axis is in the plane, but along [11bar0] that means across the stripes. This cross magnetization induces ferromagnetic dipolar coupling between the spin blocks in adjacent stripes, which are preformed by exchange interactions. The resulting superferromagnetic phase transition is therefore driven by dipolar interactions.