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The Cathedral of Our Lady of Chartres

The Cathedral of Our Lady of Chartres, is a medieval Roman Catholic cathedral located in Chartres, about 50 miles southwest of Paris.
It is considered one of the finest examples
of French Gothic architecture and is a
UNESCO World Heritage Site. The current cathedral, mostly constructed between 1194 and 1250, is the last of at least five which have occupied the site since the town became a bishopric in the 4th century.

The cathedral has three large rose windows: one on the west front with a theme of The Last Judgment, one on the north transept with a theme of the Glorification of the Virgin, and one on the south transept with a theme of the Glorification of Christ.

Source:
Wikipedia:
Chartres Cathedral.

**
Sacred geometry**

Sacred geometry is the geometry used in the planning and construction of religious structures such as churches, temples, mosques, religious monuments, altars, tabernacles; as well as for sacred spaces such as temenoi, sacred groves, village greens and holy wells, and the creation of religious art. In sacred geometry, symbolic and sacred meanings are ascribed to certain geometric shapes and certain geometric proportions.
Source:
Wikipedia, Sacred Geometry.

**
Golden rectangle**

A golden rectangle
is a rectangle whose side lengths are in the golden ratio,
one-to-phi, that is, approximately 1:1.618. A distinctive
feature of this shape is that when a square section is
removed, the remainder is another golden rectangle, that is,
with the same proportions as the first. Square removal can
be repeated infinitely, which leads to an approximation of
the golden or Fibonacci spiral.

**
Droste Effect**

The Droste effect is a specific kind of recursive picture, one that in heraldry is termed mise en abyme. An image exhibiting the Droste effect depicts a smaller version of itself in a place where a similar picture would realistically be expected to appear. This smaller version then depicts an even smaller version of itself in the same place, and so on. Only in theory could this go on forever; practically, it continues only as long as the resolution of the picture allows, which is relatively short, since each iteration geometrically reduces the picture's size. It is a visual example of a strange loop, a self-referential system of instancing which is the cornerstone of fractal geometry.
Source:
Wikipedia,
Droste Effect.