Photoemission investigations of URu2Si2

A brief review of selected experimental photoemission works on URu2Si2 spanning almost 25years is presented. We focus on the areas of importance for both the paramagnetic (PM) and hidden-order (HO) phases, where photoemission provides direct and strong evidence for: (i) f-d hybridization, (ii) presence of hybridization gap, (iii) details of the massive reconstruction of FS upon transition and (iv) a non-integer valence likely close to 2.6. While most of the FS reconstruction details have been mapped and are now known, the most recent high resolution and low temperature ARPES studies reveal novel electronic structure features related to HO. No single ARPES experiment so far captures all of the phases appearing in this system as temperature is lowered.