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New perspectives to save cultural heritage
Altan, M. Orhan

G. Pantazis a , R. Korakitis 3 , E. Lambrou 3 , D. Sinachopoulos b
a School of Rural and Surveying Engineering, National Technical University of Athens,
9 Heroon Poly tec hniou, GR 15780 Zografos, Greece (gpanta@central.ntua.gr)
b Institute of Astronomy and Astrophysics, National Observatory of Athens
Commission VI, WG VI
KEY WORDS: Surveying monument, geodetic and astronomical measurements, orientation.
This work presents a method for the thorough research of the orientation of monuments, based on state-of-the-art geodetic and
astronomical measurements. The proposed measurement and data reduction procedures are rigorous and lead to an accurate
determination of the orientation of a monument. The term “orientation” collectively refers to: the astronomically oriented plan of the
monument, the diagram of the perceptible horizon around the monument and the diagram of the apparent path of the Sun (or other
star) as it rises above the horizon at characteristic dates. Then, the orientation is interpreted in terms of other, mostly cultural,
information about the scope of the monument and in combination with its time of construction. In retrospect, therefore, the proposed
method provides a new, independent way for the confirmation or the determination of the time of construction of the monument
within a narrow chronological range.
An analysis of the method is given (including geodetic and astronomic observations and data reduction). The presentation of the
method is best illustrated by the parallel discussion of a particular application, at the church of the Great Meteoro Monastery (within
the “Meteora Monastic Community” in Central Greece). The performed measurements are described, accompanied by the
corresponding geometrical diagrams. The orientation of the church is discussed in connection with the celebration date at the time of
construction. Finally, useful conclusions are drawn about the geometrical characteristics of the monument and the meticulous
attention shown by its constructors.
Application of the proposed method to other monuments is of great significance, since it will provide the geometric framework for a
database of oriented monuments (in the form of a Geographical Information System), which will be very helpful for the study and
preservation of our cultural heritage.
The term “orientation” refers to the position and the direction
(e.g. azimuth) of a monument at the site of its construction.
Social or religious rules and traditions explain the relation
between the orientation of the monument and the point of
sunrise or the point where a star rises on a specific date. The
solstices, the equinoxes or the date that the monuments
celebrate have great significance for the builders. With regard to
buildings, their placement, orientation, shape, material, the time
of decoration, all give us important information about the
cultural activities of a civilisation (Hoskin, 2001).
Archaeoastronomy has delivered insights about the orientation
of prehistoric and historical tombs, temples and other buildings
world wide. Several celestial bodies were used for the
orientation of buildings in many cultures, the one mostly
preferred among them being the Sun. This rule was already
followed on Neolithic (Hoskin, 2001), Egyptian (Spence, 2000),
Ancient Greek (Papathanasiou, 1994), Minoic and Mycenean
(Liritzis, 2000) and Byzantine monuments (Pantazis, 2002).
Sunlight has been very important for Byzantine architecture.
The natural light and the direction of illumination of the altar of
a temple influence the choice of its orientation. Specifically, the
orientation of Byzantine Orthodox Churches is determined by
the illumination of the holy altar (Potamianos, 2000). The altar
is of special importance in the Orthodox Church because the
priest stays mostly there and performs the Holy ceremony, so its
position is very well defined. All churches, as determined by
tradition, should fulfill the proper illumination of the altar
during the time of Eycharist. Generally speaking, according to
Patrologia Greaca (4 th century AD) the recommended
orientation for a church was set by the Holy Fathers to East -
West (Migne, 1863).
The method described in this work is based on the combination
of the following procedures (Pantazis, 2002):
- The geometric determination of the main axis or of any other
special direction of the monument, which is achieved by
establishing an accurate geodetic network around the monument
and creating its digital plan produced by accurate geodetic
methods and instruments.
- The determination of the astronomical azimuth of a base of the
network using observations of Polaris and transferring it, by
geodetic methods, to the main axis or any other direction of the
- The geometric determination of the boundary line (silhouette)
of the perceptible horizon, as seen from a specific position of
the monument, through geodetic measurements.
- The reconstruction of the apparent diurnal path of the Sun, or
any other star, for characteristic dates (e.g. celebration day of
the divinity to whom the temple is dedicated, solstice, equinox
etc.) related to the time of construction.
Combination of the above data permits the determination and
the interpretation of the orientation of a monument with the
appropriate precision and reliability. There is also the possibility
to date a monument according to its orientation with a narrow