The Octagon is located on the south side of the lower Curetes Street and is a tomb monument that, together with many honorific monuments, bordered this area of the street in antiquity. Over a square ground plan, a socle building rises up; this is clad with orthostat blocks and contained the tomb chamber within its core. Above the socle, the octagonal main storey was elevated, comprising a massive cella surrounded by eight fluted columns with Corinthian capitals. The entablature consists of a three-fascia architrave and a palmette frieze; above this was a sima with consoles, which were alternately supported by griffins and acanthus leaves. A steep, eight-sided pyramidal stepped roof, crowned with a large sphere, completed the structure.

Today, only the square socle is in situ on the Curetes Street. The majority of the preserved architectural elements have been gathered together into a depot for the display of worked architectural stones, to the south of the Library of Celsus. The construction elements of one bay of the monument are today exhibited in the Ephesos Museum in Vienna.

The monument was excavated in 1904 under the directorship of R. Heberdey. In his excavation report (R. Heberdey, ÖJh 8, 1905, Beibl. 70 ff.), Heberdey mentioned the building, its octagonal form and "several distinctive features". At first he interpreted the structure as a victory monument, similar to the Round Monument on the Panayırdağ.

In the surrounding area of the socle, numerous additional building elements were excavated, which can be assigned to the monument. The orthostat slabs, upon which two imperial edicts of the 4th century A.D. were made public (Inschriften griechischer Städte aus Kleinasien 11, 1 [1979] = IvE 42. 43), were replaced in their original positions on the socle, positions which were identified by the find-spot of the slabs as well as by the cuttings of the corner blocks and the position of the inscribed texts. In 1926 M. Theuer carried out a follow-up investigation of the socle in order to clarify the purpose of the building. At this time a barrel-vaulted tomb chamber came to light with a simple marble sarcophagus containing a burial devoid of grave goods (J. Keil, ÖJh 26, 1930, Beibl. 44).
After the building was uncovered, the excavation architect W. Wilberg created a stone-by-stone drawing (missing today), a reconstruction drawing and a description of the building, which remained unpublished for a long time.
A thorough analysis and classification was first undertaken by W. Alzinger, who presented the structure using the building description of W. Wilberg and the section produced by M. Theuer (W. Alzinger, Augusteische Architektur in Ephesos, SoSchrÖAI 16 [1974] 40-43 Abb. 27-31).
Although the building was indeed mentioned in a variety of publications, a systematic and accurate reconstruction, as well as a detailed investigation of the structural finds, failed to appear for many decades.
Research into the identity of the occupant of this prominently located sepulchral building was carried out by H. Thür, who wants to identify the occupant as Arsinoe IV, sister of the famous Cleopatra and murdered on her instruction at Ephesos in 41 B.C. (H. Thür, ÖJh 60, 1990, 43-56).
In the course of archaeological follow-up investigations, excavations were carried out between the south side of the Octagon and the tabernae in 1993 and 1999. The evaluation of the finds from these excavations, by A. Waldner, resulted in a date of ca. 20 B.C. for the cessation of building work at the unfinished rear face of the Octagon.

The object of the current project is the detailed recording of all structural elements which, based on the contemporary state of knowledge, can be assigned to the monument, as well as the accurate reconstruction of the building which is preserved to a large measure and which probably significantly determined the appearance of the lower Curetes Street up until late antiquity. Within the framework of the project, however, particular consideration is given to the manner in which the monument should be presented in the context of the ruins of the city. Due to its conspicuous location and the large number of preserved building elements, a reconstruction in the form of an anasylosis has also been taken into account. Within the course of current work, a restoration concept as well as the planning essentials for a reconstruction of the building should be produced.
For the measuring of the socle building and the recording of the more than 170 building parts, the most up-to-date 3-D surveying system was employed. For overview scans, such as for example the remains still in situ on the Curetes Street or the restored building elements in the Ephesos Museum in Vienna, the laser scanner LMS-Z 420i, developed by the company RIEGL-Laser-Measurements-Systems, was employed, which covers a comparatively large measurement range. The stripe light projection system PT-M 1024, developed by the Fraunhofer-Institut in Munich, delivers detailed measurement results in connection with QT-Sculptor software. Thanks to cooperation with the Institute for Building Research and Historic Preservation, in the field of Architectural History and Building Research of the Technical University of Vienna, this piece of equipment is able to record the smaller architectural elements as well as consolidate the survey data for the larger objects. To a large extent, it was possible to conclude the survey work during the 2007 campaign.

The output of both measurement systems are point data, so-called point clouds, which during postprocessing were worked up in a number of steps to closed surface models. The three-dimensional models of the building elements now offer the opportunity to implement the accurate reconstruction of the Octagon in virtual space. A variety of combinations can thereby be tried out, in order to assign all the construction elements, step by step, to their original position in the building.
After the conclusion of this work, the three-dimensional model provides on the one hand all the information necessary to be able to create ground-plans of the individual levels, sections, and, eventually, completed plans including the necessary additions and technical associations for the presentation of the ruins. Furthermore, the virtual space creates an effective framework for the representation of a reconstruction with varying dimensions and from any perspective, and for simulating the optical effect at the site.
Parallel to the measurement and visualisation work, all of the components of the building will be investigated by restorers with regard to whether or not they can be reused. In the foreground here is the cleaning of the still-extant building matter and its protection against further damage.

Picture Captions
Fig. 1: View, section and groundplan, after W. Wilberg and M. Theuer (© ÖAI)
Fig. 2: The current condition of the socle building on the lower Curetes Street (B. Thuswaldner)
Fig. 3: Depot for architectural elements to the south of the Library of Celsus (B. Thuswaldner)
Figs. 4. 5: The Octagon after the excavation of 1904 (© ÖAI)
Fig. 6: Postprocessing steps from the point clouds to the completed surface model (B. Thuswaldner - R. Kalasek)
Fig. 7: The virtual anastylosis of the Octagon (B. Thuswaldner - R. Kalasek)
Fig. 8: 3-D-model of the entire situation on the lower Curetes Street (B. Thuswaldner - R. Kalasek)

Bibliography (selected):
S. Ladstätter (Hrsg.), Neue Forschungen zur Kuretenstraße von Ephesos. Akten des Symposions für Hilke Thür vom 13. Dezember 2006 an der Österreichischen Akademie der Wissenschaften, DenkschrWien = AForsch (in Druck, 2009).
B. Thuswaldner - S. Flöry - R. Kalasek - M. Hofer - Q.-X. Huang - H. Thür, Digital Anastylosis of the Octagon in Ephesus, Association for Computing Machinery (ACM) Journal on Computing and Cultural Heritage (in Druck).
B. Thuswaldner - R. Kalasek, The Virtual Anastylosis of the Octagon in Ephesus, in: J. Al-Qawasmi - M. A. Chiuini - S. El Hakim, Digital Media and its Applications in Cultural Heritage (DMACH) 4, 2008, 95-113. S. Cormack, The Space of Death in Roman Asia Minor (2004).
C. Berns, Untersuchungen zu den Grabbauten der frühen Kaiserzeit in Kleinasien, Asia Minor Studien 51 (2003).
I. Kader, Heroa und Memorialbauten, in: M. Wörrle - P. Zanker (Hrsg.), Stadtbild und Bürgerbild im Hellenismus, Vestigia 47 (1995) 199-229.
F. Rumscheid, Untersuchungen zur kleinasiatischen Bauornamentik im Hellenismus (1994) I 160 ff.; II 19 Kat. 48.
H. Thür, Arsinoe IV, eine Schwester Kleopatras VII, Grabinhaberin des Oktogons in Ephesos? Ein Vorschlag, ÖJh 60, 1990, 43-56.
W. Oberleitner - K. Gschwantler - A. Bernhard-Walcher - A. Bammer, Funde aus Ephesos und Samothrake, Katalog der Antikensammlung II. Kunsthistorisches Museum Wien (1978) 95-98.
W. Alzinger, Augusteische Architektur in Ephesos, SoSchrÖAI 16 (1974) 40-42.
J. Keil, XV. Vorläufiger Bericht über die Ausgrabungen in Ephesos, ÖJh 26, 1930, Beibl. 41 ff.
R. Heberdey, VII. Vorläufiger Bericht über die Ausgrabungen in Ephesos, ÖJh 8, 1905, Beibl. 70-72.

Project promoter: ÖAI / Ephesos Excavation
Financing: Society of the Friends of Ephesos (http://www.ephesos.at)
Coordination and scientific analysis: Barbara Thuswaldner
3-D Visualisation: Robert Kalasek
Damage findings and restoration: Martin Pliessnig
Damage findings and stonemason work: Tilman Borsdorf
Scientific consultation: Hilke Thür, Marina Döring-Williams
Scientific groups of experts: Martin Bachmann (German Archaeological Institute Istanbul), Thomas Käfer (Aphrodisias Excavation, New York University), Gerhard Paul (Aphrodisias Excavation, New York University), Klaus Nohlen (FAB, University of Applied Sciences Wiesbaden), Ebru Torun (Sagalassos Excavation, Katholieke Universiteit Leuven).

Contact:
Barbara Thuswaldner