New light on the relationship between the Montecitorio Obelisk and Ara Pacis of Augustus

Bernard Frischer, John Pollini, Nicholas Cipolla, Giuseppina Capriotti, Jackie Murray, Molly Swetnam-Burland, Karl Galinsky, Chrystina Häuber, John Miller, Michele R. Salzman, John Fillwalk, Matthew R. Brennan

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The article takes as its point of departure recent work [Frischer forthcoming] critiquing the theory of Edmund Buchner about the relationship of the gnomonical instrument known as the Horologium Augusti and the Ara Pacis Augustae. As a result of this critique, the Montecitorio Obelisk could be situated with greater precision on the map of the city. A computer simulation showed that Buchner erred in positing that the shadow of the Montecitorio Obelisk went into the center of the Ara Pacis on Augustus’ birthday. In this article, computer simulations are used to develop a post-Buchnerian interpretation of the relationship of the obelisk and altar. Over 230 hitherto unrecognized solar and shadow alignments are reported. The first part of the article defines four zones around the monuments where the solar and shadows observations were made. In the second part of the article, specialists interpret the significance of the annual solar and shadow spectacle from various points of view. The conclusion synthesizes the results, arguing that the monuments were intentionally aligned and situated in order to propagate the same message as the one inscribed on two sides of the Montecitorio Obelisk [CIL 6.702 = ILS 91]: that Augustus was a devoted worshipper of the sun god (Sol), who brings Rome victory in time of war, and prosperity in time of peace through his earthly representative, the emperor.

Original languageEnglish
Article number2
JournalStudies in Digital Heritage
Issue number1
StatePublished - Mar 23 2017

Bibliographical note

Funding Information:
1 I am pleased to acknowledge that the research project on which I report in this paper was supported by the following: Zukunftskolleg, University of Konstanz; School of Informatics and Computing, Indiana University; the Netherlands Institute for Advanced Study in the Humanities and Social Sciences; the National Science Foundation (grant #IIS-1014956). I take this opportunity to thank Francesco Prosperetti, Superintendent of the Soprintendenza Speciale per il Colosseo, il MNR e l’Area Archeologica di Roma, for permission to take geological cores and to pursue campaigns of ground penetrating radar in the area of the Campus Martius where the Horologium Augusti is suspected to have extended. For her support and cooperation, I am grateful to MartaBaumgartner,theSuperintendency’s officialresponsiblefortheareain question. ImadinebtedotMarinaaSpelli Ragni and Anna Maria Reggiani, the members of the Scientific Advisory Committee for this project, for giving so generously of their time, advice, and insights. I wish to thank the following for their indispensable help in researching this article: Paolo Albèri Auber, Maria Elena Bertoldi, Heinz Beste, Michele Bilancia, Ralf Bill, Matthew R. Brennan, Jane Crawford, David Dearborn, Stefano Floris, Egbert Friedrich,GuidoGiordano, Chrystina Häuber, Robert Hannah, Lothar Haselberger, Paul Humphreys, GüntereLonhardt, Paolo Liverani, Frans Maes, Ismini Miliaresis, Adalberto Ottati, Alberto Pichardo, Marco Ricci, Pietro Roccasecca, Rosella Roccasecca, Orietta Rossini, Michael Schütz, Claudio Soccodato, Magda La Torre, Giuseppe Tosti, Vance Tiede, Ursula Vedder, and Georg Zotti. I express my deep appreciation to Sig. Giuseppe Brunelli for permission to visit, survey, and take a core through the section of the meridian located in the basement of the building he owns at Via di Campo Marzio 48, Rome. I thank Sig. Brunelli’s staff, especially Carla Coglitore and Giuseppe Cantiello, for their help and cooperation in arranging many visits to the site. I am grateful to Christof Schuler, Director of the Kommission für Alte Geschichte und Epigraphik of the German Archaeological Institute, Munich, for permission to consult the Edmund Buchner Archive and to publish the archival materials used in this article; and to Ortwin Daly, Director of the German Archaeological Institute, Rome, for permission to consult Edmund Buchner’s geological cores as well as documents in the Friedrich Rakob Archive. Finally, I am happy to acknowledge the contributions made by the three anonymous referees of this paper. They are clearly highly informed, qualified, and perceptive readers, and their input has improved this paper in numerous ways. Peer review works! 2 Hereafter also called the “gnomonical instrument,” “gnomonical device,” or “calendrical device”. The Latin nomenclature used for the device is either Horologium or Solarium. All these terms are used interchangeably in this article.

Publisher Copyright:
© 2017 SDH Open Access Journal


  • Ara Pacis Augustae
  • Archaeoastronomy
  • Horologium Augusti
  • Montecitorio Obelisk
  • Stellarium
  • Unity

ASJC Scopus subject areas

  • Classics
  • Archaeology
  • History
  • Museology


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