Abstract: One-dimensional conductors are the wires that will connect the circuits of tomorrowÕs nanoworld, so it is important to characterize their possible conducting phases. We study a novel one-dimensional wire state which arises at the corner of two quantum Hall systems joined at a 90¡ angle, and observe both metallic,Êcritical,Êand insulating 1D behavior. Such non-planar confinement structures are unconventional for the quantum Hall effect and reveal the first observation of a macroscopic one- dimensional state whose conductance increases with decreasing temperature. This system can map out generic properties of one-dimensional disordered conductors since the metallic, critical, or insulating character is tunable with an external parameter, the magnetic field.