CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
spatial analysis about proximity and buffering around the 
geographical objects. In Bergama, this operation is realized 
for the main street axis and edifices of different historic 
periods in order to find out the structures neighbouring 
them in the contemporary town. The elements of 
contemporary town falling into the buffer zone require 
special care due to the possibility of material existence of 
their continuation beneath the contemporary tissue or just 
due to being closed to the important axis or edifices of 
different historic periods, (figure 3). 
Presentation of Results: Data Visualization, Output and 
Reporting: Although hard copy of the results of the analysis 
and evaluations can be provided in the form of maps, charts, 
reports and tables easily, this study is primarily designed to be 
used in the digital environment over the existing maps by the 
decision-makers. In this choice the aim is not to allow 
undervaluing the outcome of this study by treating them as 
simple analysis sheets and by forgetting that it is a system that 
should be managed and updated continuously. Therefore, data 
coming from the assessment of historical stratification are 
integrated into the attribute table of the related geographical 
objects of the contemporary urban form. Thereupon, a heritage 
information system, which contains all the necessary 
information for identification, for characterizing historical 
stratification and for conservation decision-making is provided. 
It is also possible to present and share the results with the end 
users over Internet, which has not yet been realized for the case 
of Bergama. 
Figure 3. Results of the assessment of historical stratification 
showing the sensitivity areas and traces over the 
existing map of Bergama. 
3. CONCLUSION 
The decision supporting study prepared for Bergama provides 
comprehensive information about the historical stratification of 
the town, which should be considered in various levels of the 
conservation decision-making process. In order to achieve this 
information, GIS based assessment method of the study utilizes 
huge amounts of data in various formats, scales and details 
concerning all the layers making up the contemporary town. 
Various analyses provided over these complex data show that 
their integration into the conservation decision-making process 
is essential, or otherwise the decisions made are not in 
accordance with the historical stratification of the town. The 
best proof of this is the comparison of the current conservation 
areas with the historical stratification of the town (figure 4). 
Figure 4. Comparison of the current conservation areas with 
the historical stratification of the town. 
Hence, this study proved that GIS is an appropriate tool to 
realize such a system. GIS have many advantages and potentials 
to be utilized as an integral part of such an assessment method, 
whereas, they have also some shortcomings as they are not 
softwares especially produced or enhanced according to the 
requirements of such a study. The important advantages of GIS, 
which are recognized through this study, can be summarized as: 
• the ability to integrate different types and formats of data, 
• allowing the classification of complex data to obtain their 
easy and effective utilization, 
• providing analysis over both spatial and attribute data, 
• presenting an integrated environment where data produced 
in other softwares can be used, 
• offering a highly precise environment. 
Their comparison reveals that, the areas having the same 
stratification are subject to different conservation regulations, 
which causes the destruction of the existing historical 
stratification instead of its conservation (Bilgin Altinoz, Erder 
1999). 
Besides the study also shows that, the data about the historical 
stratification differ at every point of the multi-layered town. 
Hence, it is recognized more apparently that in a multi-layered 
town like Bergama, it is not possible to make decisions over 
generalized information. Thereupon, area-based conservation 
decisions are not sufficient for multi-layered towns. The 
decisions should be built upon the Area-based information, 
which is supplemented with more detailed information 
concerning the stratification of the components of urban form. 
This study also made obvious that, with conventional 
techniques it is not possible to accomplish such a complex 
study which requires altogether utilization of huge amounts of 
data in various formats, details and scales. Besides, information 
on historical stratification is dynamic, as it changes according to 
the results of new scientific researches and excavations 
concerning different historic periods, as well as according to the 
changes occurring in time within the contemporary town. 
Therefore, coping with data concerning historical stratification 
necessitates a flexible, dynamic, and continuous system. When 
prepared with conventional techniques and tools, it becomes a 
project once prepared, while with GIS it becomes a system 
continuously managed.