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The CSA Propylaea Project: A Non-Specialist's Introduction
Oddly enough, we know very little about architectural planning in classical Greece. We are reasonably sure that drawings were not used, and there is good evidence, both physical remains and inscriptions, that models of some parts of buildings (column capitals, for instance) were made to guide the masons as they carved details on the buildings themselves. Our only building plan from the classical period, for a naval arsenal to be built near one of the harbors of the Piraeus, is an inscribed description entirely in words. It named the architect and specified most of the features and dimensions of the building. It also indicated that some matters were yet to be decided and would be specified on site, in some cases by models and in some by the architect himself.
There are indications in the inscription that the architect, not surprisingly, had determined the dimensions of rather small parts of the structure implicitly, because those dimensions were required by the canons of the day or were implicit in construction requirements. Nonetheless, we remain mostly in the dark about the planning process and must fall back on the etymology of the term architect, meaning master craftsman originally and indicating that, at least at the outset, the architect was more a foreman than a planner.
CSA Director Harrison Eiteljorg, II, has long been intrigued by the general question of architectural planning in antiquity, hoping to find indications of the change in duties of the architect from master craftsman to master planner. The Propylaea seems to hold some answers to those questions.
The Propylaea (see this page for the Wikipedia article about the Propylaea) was the entrance building for the Acropolis; it was built between 437 and 432 B.C. (but left unfinished), directly after the construction of the Parthenon. The building started going up before the sculpture on the Parthenon had been completed, though the structural portions of the Parthenon had been finished and the temple had been dedicated. The Propylaea was a grand building, fitting for its use as the gateway to the Acropolis, and it has been used ever since as a model for grand entrance structures. Its central core has been used as a model not only in antiquity but in more recent structures as the Brandenburg Gate in Berlin.
The Propylaea was not only large and grand; it was also complex. (See this page for a plan.) Indeed, it is apparently the first monumental building of the classical period that was planned to be more complex than a simple rectangle or a cylinder. It was, from the very beginning, planned that there would be a central core plus two wings on the west side (facing toward one another) and two more wings on the east side (not facing one another but facing east, like the central core, toward the heart of the Acropolis).
Although the core and the western wings were nearly complete, the two east-facing wings had scarcely begun when construction ceased on the entire building. Stubs of walls show the intent of the builders, as do cuttings for roof members of the eastern wings; those cuttings can be seen today in the exterior faces of the walls of the central core of the building. However, neither eastern wing went beyond a very early stage. In addition, the southern of the two east-facing wings seems - by virtue of the presence in situ of older remains not removed as would ultimately have been required - to have been abandoned rather early in the construction process.
Since they are unfinished, we cannot be sure of the final appearance of the eastern wings, but the scale of those wings - heights of columns and roofs - was certainly much smaller than the scale of the central portion of the structure. The finished western wings are clearly at a smaller scale as well.
The complexity of the Propylaea - its use of wings of differing scales, for instance, making roofing very complicated - required a level of planning not needed for buildings designed in simpler shapes. In addition, the typical grand structures of the day - temples and stoas - had many ancestors and rather fixed notions of their ultimate appearance. Therefore, the advance planning required for such buildings was minimal; relatively gross dimensions more or less fixed everything else and permitted experienced masons to work with few specifications. The architect could count on the experience of all involved to take care of many problems, and, in fact, the most difficult aspects of construction were so subtle that a modern architect using the latest equipment would be hard-pressed to design and document those subtle construction matters. (Columns and walls lean almost imperceptibly, and the column-bearing surfaces of temples, the outer ring of the floor, were intentionally designed with a subtle curve rising from the corners to the center of each side. The rise, however, is so slight that even a modern architectural plan would not effectively show that rise at a scale intended to permit the plan to be shown on a 6-feet-long piece of drafting paper. [Note: A scale of 1:40 would permit the north or south elevation of the Parthenon to be drawn on a single sheet of drafting paper 72 inches long. At that scale, the rise in the long sides of the building from corner to center would be 0.108 inches - less than 1/8 of an inch. Thus, the change in height from one side of a stone to the other would amount to less than 5 thousandths of an inch, much less than the thickness of the lead in a good drafting pencil.]
The Propylaea, precisely because of its complexity, had no real predecessors, no models on which the problems of uniting the parts had already been worked out. (Even those scholars who believe that the predecessor of the Propylaea was as large as the central core of the Propylaea itself would not posit wings attached to that central core of that older iteration of the Propylaea.) As a result, the Propylaea seems to be a key structure in the history of Greek architecture. It requires planning both because it is unique and because it is complex. It seems to mark a new kind of structure - one without predecessors to act as guides to its design and construction.
This interest in the building as a landmark in the history of architecture was one of the reasons CSA Director Harrison Eiteljorg, II, began the work that culminated in the CSA Propylaea Project. The unique position of the Propylaea had become clear to him over time, and he had begun to see the structure as key to an understanding of Greek architectural planning by the late 1990s, even giving some talks about it as the first self-consciously unique and innovative building in ancient Greece.
As Dr. Eiteljorg grew to realize how important the Propylaea was in the history of architectural planning, he was also getting to know the man in charge of modern work to restore parts of the building, the Greek architectural historian, Dr. Tasos Tanoulas. They met first in the 1980s when Dr. Eiteljorg was still working on the predecessor of the Propylaea, the so-called older propylon, and they became friends, no doubt in part because of their mutual interest in the entrances to the Acropolis over the centuries.
As Dr. Tanouls studied the Propylaea, of course, he published important work showing what he was learning, and that work included carefully drawn and dimensioned elevation views of two of the walls of the NW wing of the building. Seeing those drawings and the three-dimensional survey information noted on them encouraged Dr. Eiteljorg to think of creating a full, three-dimensional, computer model of the structure. With that much information (three coordinates for every corner of every block), he envisioned the real possibility of understanding the design of the structure, what the architect had intended, what he had foreseen, and what he had missed because of the novel nature of the building. (By then Dr. Eiteljorg had recognized certain difficulties and had begun to think the building had not been completed, at least in part, because adjustments in the plan were required.)
With Dr. Tanoulas and his engineer on the restoration project, Maria Ioannidou, Dr. Eiteljorg created a grant proposal for what was called the CSA Propylaea Project, and funding was received from the Samuel H. Kress Foundation. The computer model was the aim, and included in the grant proposal was the idea that all information about the building should and would be freely available via the web.
The team started to work immediately but hit a substantial roadblock quickly. It turned out the the three who had together prepared the proposal had not fully understood one another. The three-dimensional survey work demonstrated in the drawings of two walls of the NW wing was anomalous. Most walls of the Propylaea had not been surveyed in all three dimensions. Instead, the height and length of each block had been measured, not the position of each corner, complete with its depth in the wall.
As a result, the project became a technical one. Instead of translating fully surveyed points into a computer model, it became necessary first to survey the building to obtain those points. That sounds rather simple, but it is not, and years were spend trying to find the best ways to accomplish the survey. Various modern techniques were tried and finally, in December of 2007, a system that seemed to offer the best possible survey results was tested. It was based upon a portable scaffolding structure sent from the US to Athens to be erected where needed in the building and moved from place to place as required. A member of the team could stand on the scaffolding to hold a survey target on any point of interest, and another member of the team could survey the designated point from the ground with a modern surveying instrument (a total station). The system developed was not fully ready then, but additional pieces were created during the following spring and summer so that the scaffolding could be raised and lowered by one or two people and the system could function as required without requiring many people to position it.
By the time the new system was ready to be put to work, however, Dr. Tanoulas had changed his position about the data gathered by the project. Instead of gathering information that would be available to the team for the building of the computer model (and ultimately to anyone via the web), any information gathered in the future - at the project's expense - would belong the Greek Ministry of Culture and would be made available to the team (and/or others) under such terms and conditions as might, from time to time, be imposed by the Ministry of Culture. As a natural consequence, the project was terminated, and remaining funds were returned to the Samuel H. Kress Foundation.
Despite the termination of the CSA Propylaea Project, Dr. Eiteljorg remains committed to learning more about architectural planning in ancient Greece. It is his hope that the knowledge gained, incomplete though it may be, will permit the continuation of the search for the real planning that underlay the Propylaea. At the moment, for instance, it seems that we can look to the length of the blocks of the structure as the most likely building module.
This web site provides access to the data resulting from the work, including information about the survey and computinmg processes used by the team. Since the project was not completed, however, interpretive results are not presented here. (There are on-going efforts to determine the role of the architect in the classical period, and readers interested in those efforts may wish to follow the blog listed on the left or to read the web pages that present the same discussions in a different format.)
The data generated by CSA Propylaea Project are entirely digital; that is, the data are all in computer files. One advantage of that is that all the data may be shared over the internet. For instance, even older, film-based photographs have been digitized so that anyone with a computer can see them. (The digital photographs may also be manipulated to improve their utility, though the originals are always retained.)
The more important advantage of using only digital data arises from the critical advantages of digital records of three-dimensional objects, in this case, of course, the Propylaea. The project did not produce typical architectural drawings but did produce computer models of parts of the structure. (The standard, generic name for computer programs that model buildings or other complex geometric shapes is CAD, short for computer-aided - or assisted - drafting or drawing.) Using CAD to make a model of the structure provides two critical advantages over traditional paper drawings. First, the data in the computer may be far more precise than on a drawing, retaining the full precision of the survey data. The scale of any paper drawing places firm physical limits on precision, with the smallest measurable distance determined by scale. 1
The other great advantage of the CAD model in this work is that all points are three-dimensional. That is, no point need be assumed to lie in the plane of its encompassing wall or otherwise on some predetermined plane. Each surveyed point occupies a specific place in space as determined by three coordinates. A physical drawing, on the other hand, shows only two dimensions. Two drawings from different vantage points (typically a plan and an elevation) may make it possible to determine all three coordinates of a given point in the drawings, but in a CAD model any point may be queried at any time to show all three coordinates, whether one is looking at that point in a plan, an elevation, or a perspective view. Once again, the survey information is more fully and precisely retained in the CAD model. In addition, 3D views can readily be created by a CAD program - with the viewpoint being virtually any point in space. (For more information about CAD software and its application to archaeology, this old and somewhat outdated booklet remains a good introduction. Other resources available from this page may also be of interest; they are more technical but also more current.)
Text of note 1.The limits apply both to the draftsman and to the user of a paper drawing. The draftsman may only make so fine a discrimination when putting pen or pencil to paper; regardless of the draftsman's skill, the user can only interpret the drawing to a certain level of fineness. For instance, if a line has thickness, as it must to be seen, does one measure to one side or the other or the middle, assuming the middle can be determined?) A CAD model uses - and retains - the coordinates provided by survey, regardless of precision (necessarily treating 1 as effectively equivalent to 1.0000) and generates drawings from those numbers. CAD drawings may be marginally more precise than hand-made drawings, but any user is still constrained by the problem of interpreting that drawing. The great advantage of the computer model is that the number associated with a point is retained in the CAD model as its core data, and it can be retrieved at any time (with full precision). Thus, the precision with which a building is surveyed is retained by the CAD model while it will surely not be retained in a medium depending upon the drafting and interpretation process.
Note the color differences between the top photo and the lower one. This reflects the color of the sunlight at the west end of the Acropolis, with the morning light being cool and the afternoon light warm, growing steadily warmer toward sunset.