This work is licensed under a Creative Commons Attribution 4.0 International License.-- et al. ; Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon monoxide/platinum system. We curve a platinum crystal around the high-symmetry (111) direction and carry out photoemission scans on top. This renders the spatial core-level imaging of carbon monoxide adsorbed on a 'tunable' vicinal surface, allowing a straightforward visualization of the rich chemisorption phenomenology at steps and terraces. Through such photoemission images we probe a characteristic elastic strain variation at stepped surfaces, and unveil subtle stress-release effects on clean and covered vicinal surfaces. These results offer the prospect of applying the curved surface approach to rationally investigate the chemical activity of surfaces under real pressure conditions. ; We acknowledge financial support from the Spanish Ministry of Economy (Grants MAT2013-46593-C6-4-P and MAT2013-46593-C6-2-P ), Basque Government (Grants IT621-13 and IT756-13). A.L.W. acknowledges support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-SC0012704. AXBR acknowledges support from the Basque Departamento de Educación and the UPV/EHU through the Zabalduz program. AXBR, PCS and DSP acknowledge the Deutsche Forschungsgemeinschaft through the Sonderforschungsbereich 1083. ; Peer Reviewed