The author compares the founding of Constantinople, the second Rome, by Constantine with the mythical founding of Rome by Romulus, and suggests that both rituals involved facets of Domezilian trifunctionality, modified by N.J. Allen's function. Key Words: Constantine, Romulus, Georges Dumezil, Byzantium, Rome, IndoEuropean trifunctionality, fourth fitaction Any 'founding king' will by definition be a figure of some mystery, combining the features of the eponym or ultimate ancestor of the polity with the special potencies integral to one who literally makes Something out of Nothing. In this paper I intend to try to find a pattern of mutuality and equivalence in the careers of two such founders: Romulus, held responsible for the very beginnings of Rome, and Constantine the Great who - approximately a millennium later - would found the Second Rome, named after himself, that is the city of Constantinople. This-serious project is made somewhat easier because of the recent work of N. J. Allen, who, in explicating an important addendum to the trifunctional theories of Georges Dumezil1 which Allen has termed the Fourth Function, has examined and reinterpreted the Romulan evidence in some detail: Romulus has, in fact, become Allen's ideal or exemplary Fourth Function ruler (Allen 1987, especially Allen 1996). Here Allen followed Dumezil in finding that Romulus had combined in himself the key powers of all three of the I-E functions - i.e., (in bare outline) sovereign power, military prowess, encouragement of fecund growth (Dumezil 1966/70: 25). The Romulan stance as 'first king' and as 'magical king' was supported by this combinatory mystery, and, even more, was dramatized by the fact that the Founder was succeeded by kings who evidently represented each of the three Functions in turn: Numa Pompilius as lawmaker, Tullus Hostilius as warmaker, and Ancus Marcius as one who conforme d'alleurs a l'esprit de la troisieme fonction (Dumezil 1968: 273). I do not have the time here to deal with every aspect of Allen's F4 theory, but I do want to underscore certain of his main descriptive points concerning the Romulan biography (other then this king's omnifunctional competence): (a) his semi-divine parentage, Co) the fact of the auspici, that is, the divine or heaven-sent (extraordinary) communication that authenticated Romulus's particular form and vision of his City and, as well, the installation or mobilization of the (ordinary) sacra that followed, (c) the sacrifice/fratricide, wherein Romulus was held ultimately responsible for the death of his twin, Remus, and (d) the death or 'immortalization' of Romulus himself. The drama of Romulus and its details is taken mainly, if not exclusively, from Livy, and so shows that historicizing of myth to which the Romans are known to have been addicted. Now I would like to take up the Second Foundation, and Constantine as the Second Founder; here, I suggest, we confront an event in history that has been extensively recast or surrounded in myth, seeing the founder-figure of Constantine the Great drawn back into what Gilbert Dagron appropriately calls Constantinople imaginaire (Dagron 1984), especially in the source called the Patria, and his deeds laid out or explicated in what Dagron terms patriogsaphy. First, we must react to the overt resemblances that can be set up between one city's foundation and the other - and here we will already have taken note of the infiltration of elements of mystery and the supernatural into whatever bald historical account we possess. We initially assume that a Founder must deploy that combination of potencies seen so clearly in Romulus; Constantine will in fact show these, but we also have to deal with any possibility of a later parallel with the semi-divine paternity of Romulus, identified as a son of Mars. To find this parallel - to make Constantine semi-divine - is not a simple matter, but we know that aspects and even the natures of emperors and gods were thoroughly confounded early on in the Principate, and in the Tetrarchy devised by Diocletian, some decades before Constantine won supreme power, symbolic godhead was assigned to both senior and junior rulers: Diocletian, for example, was declared to be assimilable to Juppiter Maximus Optimus, his junior Maximianus to Hercules, the Divine Son (Alfoldi 1970: 44). …