A series of data from the period 1896-1901 concerning the erection of the Arsakeion New Buildings have resulted from the research carried out by the author of this article in the framework of his Ph. Dissertation entitled “The Athenian Monumental Edifices of the Nineteenth and Early Twentieth Century: Investigation of Construction and Static Methodology (1834-1901). In brief, the initial decision of the Philekpaideutiki Society Board was the Vouros mansion and parts of the Tositseion School and the Kindergarten edifice on Stadiou Street to be pulled down in order the Exoterikon Didaskaleion to be erected there, after the architectural plans by Eugene Troump, a project that, however, was never realized. In 1899 the military architect Anastasios Theophilas was entrusted to design the so-called Arsakeion New Buildings and in 1990 the Tositseion School and the neighboring buildings were demolished. On 26 April 1901 the foundations of the New Buildings were laid according to Theophilas’ designs, as they were modified by the supervisors of the project Nikolaos Balanos and Nikolaos Demadis and the expert suggestions of Wilhelm Doerpfeld. This article presents in detail the elements composing the crucial period of five years that was very important for the architectural and building development of Arsakeion.