The particular circumstance of the medieval history of Spain and Portugal, with the presence of Islam from 711 to the Christian reconquer ending in 1492 with the fall of Granada, left behind a deep influence in art and architecture. During eight centuries the Iberian Peninsula was divided into Christianity and Islam, two cultures which were confronting political and religious forces. But in spite of this confrontation, contacts and influences were frequent as it is proved by the many examples of architecture which still remain.

Being art an irreplaceable document for the knowledge of the past, Mudéjar art is the genuine artistic manifestation of Medieval Christian Spain, the expression of the artistic thought of a society in which Christians, Muslims and Jews lived together. These social circumstances made the origin of Mudéjar art possible, being the continuation of the Moorish artistic tradition in Christian Spain.

Mudéjar art does not belong strictly to Moorish art or to western Christian art, as it is a link connecting both. It is a singular event in the history of Spanish art. Mudéjar art is above all the artistic expression of medieval Spanish society, a society which was a result of political pragmatism and religious tolerance.For this reason we must consider Mudéjar art as an art which belongs to both cultures, it is therefore not strictly Christian as it is not strictly Moorish, because it nourishes from both cultural traditions to create a new form of art which materializes all the different ways of understanding social relationships in a particular time in history.
The prime factor which made it possible for Mudéjar art to come to life was the fascination which Christian society felt towards the artistic manifestations of Islam. The influence was not only in society but also to be appreciated in monuments. This is why each of the Mudéjar artistic expressions are not only influenced by the former local Islamic art, but they are also constantly enrichened by Al-Andalus’ new artistic skills which emerged along history.
The analysis of Mudéjar art should emphasize on two different aspects:
1.- The analysis of Mudéjar art should emphasize on two different aspects:
2.- That Islamic art has provided decisive structural elements in the development of Mudéjar art.

Considering Mudéjar ornamentation we must not only detect the formal motives of Islamic tradition, like stylized floral or vegetal designs (arabesques), geometrical elements (latticework and stars) or the Arabic scripts (Kufic and Naskhi), repetitive rhythm or the tendency of complete coating of almost any plain surface (horror vacui versus amor infiniti) are equally main principles of Islamic artistic composition.
Another of the structural elements of Islamic root, fundamental in the Mudéjar architectural system, are the wooden coffer ceilings, like the open collar beam roof with the typical decorative double beams.
As far as Christian elements in Mudéjar art are concerned, frequently overvalued in traditional historiography, these are owed to the fact that the majority of those who commissioned Mudéjar art were Christians, thus the function of architecture and its typology are mainly Christian. That is why Christian religious architecture predominates in Mudéjar art, with the particular exceptions of Mudéjar synagogues and mosques.

In this historical-artistic context Mudéjar art left behind a great number of monuments and decorative motives, especially wood carved ceilings. Mudéjar ceilings were characterized by the joinery of laced wood work, which is formed by extraordinarily complex decorative groups of polygons which interlace and cross alternately. This handcraft was so complicated that special knowledge of geometry was needed, apart from accuracy and precision, for which Mudéjar ceilings were highly valued being abundant in churches or important palaces.

Based on wikipedia