We present an extensive investigation of CO-induced structural transformations occurring on the reconstructed Pt(110)-(1x2) surface while bridging the so-called pressure gap between surface science and industrial catalysis. The structural changes are followed on the atomic scale as a function of CO pressure over 12 orders of magnitude, up to 1 bar, by the use of a novel high-pressure scanning tunneling microscope (HP-STM). The transition between the low-coverage and saturation-coverage structures is found to proceed through local displacements of substrate Pt atoms. The structural transformations of the Pt surface as observed by STM can be explained within a very simple picture governed by the gain in CO binding energy when CO binds to low-coordinated metal atoms. (C) 2003 American Institute of Physics.