The ATLAS ITk Pixel Detector. The biggest challenges from design to construction

Abstract As a part of the ATLAS Phase-II upgrade, the current Inner Detector of the experiment will be replaced with a new all-silicon Inner Tracker (ITk) designed to face the challenging environment associated with the high number of collisions per bunch crossing expected during the High-Luminosity phase of the Large Hadron Collider. Along the lifetime of this project, from design to prototyping stages, many difficulties have been encountered and unforeseen problems had to be solved. In this proceeding, an overview of the ITk Pixel Detector layout and the most demanding tasks faced with up to now are described.