Here we describe the design, single-molecule transport measurements, and theoretical modeling of a ferrocene-based organometallic molecular wire, whose bias-dependent conductance shows a clear Lorentzian form with magnitude exceeding 70% of the conductance quantum G0. We attribute this unprecedented level of single-molecule conductance to a manifestation of the low-lying molecular resonance and extended orbital network long predicted for a conjugated organic system. A similar-in-length, all-organic conjugated phenylethynyl oligomer molecular framework shows much lower conductance. © 2005 The American Physical Society.