Abstract:

The historical Aydos fortress is situated on the Anatolian part and to the north of the highest point of Istanbul city. Being a strategic observation point on the main road from Istanbul to Anatolia, its construction dates back to Byzantine period. Later during Ottoman time the Aydos fortress undergone many times to restoration. Nearly unique building material from nearby Paleozoic rock units was used. This is obviously Lower Paleozoic quartz arenitic sandstone rock type from Aydos formation. This very resistant rock was worked as block which in tern was attached by carbonate plaster during the construction of the fortress. Petrographical investigation under the microscope clearly shows quartz arenite rock texture with almost rounded quartz grains and fine micaceous matrix. Different rock particles were attached with carbonate cement. Finally we were able to show once more that main building materials for the ancient constructions were assemblages from nearby natural sources

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