As I've decided to begin collecting UNESCO WHS postcards, a Postcrosser from Spain very kindly offered to swap cards with me. She sent this gorgeous card of the Cathedral in Seville. Here's what the UNESCO site says about it:
"Founded in 1403 on the site of a former mosque, the Cathedral, built in Gothic and Renaissance style, covers seven centuries of history. With its five naves it is the largest Gothic building in Europe. Its bell tower, the Giralda, was the former minaret of the mosque, a masterpiece of Almohad architecture and now is important example of the cultural syncretism thanks to the top section of the tower, designed in the Renaissance period by Hernán Ruiz. Its "chapter house" is the first known example of the use of the elliptical floor plan in the western world. Ever since its creation, the Cathedral has continued to be used for religious purposes."
The stamps are pretty cool, too.
Along with the Cathedral, there is also the Alcázar (a 10th century palace) and the Archivo de Indias building (it houses important historical documents about the New World) from the 16th century on the same site.