One‐dimensional‐like Co structures 50‐A˚‐wide and 3000‐A˚‐long have been grown by decoration of the monoatomic steps of a Cu(111) surface and visualized with scanning tunneling microscopy. In order to achieve step‐flow growth, terrace width, evaporation rate, and substrate temperature have been carefully adjusted. The choice of the (111) terrace orientation and ⟨11¯0⟩ compact steps ensures a homogeneous width of the Co wires and a lateral confinement of minority‐spin electrons. ©1995 American Institute of Physics.