This volume presents part of the author's research on the Achaemenid Royal Inscriptions recovered in the ruins of the Achaemenid palaces in Susa, conducted within the framework of the DARIOSH-Louvre Project. It offers a new study of several fragmentary inscriptions in Old Persian, Achaemenid Elamite, and Achaemenid Babylonian, currently designated as DSe, DSt, DSb, DSl, DSa, DSk, DSi, DSp, D2Sb, DSj, A2Se, DSs, 'Inc. Sb', and others. The book provides a new edition of each inscription based on both published and unpublished fragments. Additionally, it introduces some new lexicons and cuneiform signs in the Old Persian language and script.