Mudejar style, or how Iberian Muslims reinterpreted Western architectural styles through Islamic influences.
The dominant geometrical character, distinctly Islamic, emerged conspicuously in the accessory crafts using less expensive materials: elaborate tilework, brickwork, wood carving, plaster carving, and ornamental metals. To enliven the planar surfaces of wall and floor, Mudéjar style developed complicated tiling patterns that have never been surpassed in sophistication. Even after Muslims were no longer employed in architecture, many of the elements they had introduced continued to be incorporated into Spanish architecture, thereby giving it a distinctive appearance.
Born in Leon and spread over much of Iberia, it was in Aragon where the level of elaboration reached its summit. Ten Mudejar buildings in Aragon are considered a World Heritage Site nowadays.
A few samples I find striking:
Saint Martin's Tower in Teruel
http://st-listas.20minutos.es/images...jpg?1239225206
Church Tower in Utebo
http://commondatastorage.googleapis....l/43807613.jpg
http://www.aragonmudejar.com/zaragoza/utebo/7ut73.jpg
Saint Mary's Tower in Calatayud
http://farm6.staticflickr.com/5270/5...a815887f_z.jpg
And some details of the Mosque and other Mudejar remains in Aljaferia Palace, in the capital city, Saragossa.
http://ies.galileogalilei.alcorcon.e....Aljaferia.JPG
http://2.bp.blogspot.com/-6NnUroTuzM...sta-isabel.jpg
http://tephotos.s3.amazonaws.com/pla...5c84b8c524.jpg
http://convistasalmundotictac.files....pg?w=614&h=819
http://www.adevaherranz.es/Arte/ESPA...20Zaragoza.gif