By Marlise Simons SEVILLE, Spain La Giralda, this city’s grand tower standing 90 meters tall, with its warm terra cotta colors and delicate brick patterns, was once called Spain’s most perfect minaret. Its twin stands in Marrakesh, Morocco, a reminder of the centuries-old ties between the countries. .Seville’s minaret has been the bell tower of the city’s Roman Catholic cathedral for the last 500 years. Today, however, many of those who walk by it daily are again Moroccans, part of the growing number of Muslim immigrants to Spain. While they have not talked about reclaiming the minaret, they are seeking permission to build a large mosque in Seville, as Islamic immigrants have in six other Spanish cities. .At the moment, Seville’s Muslims, many of them clandestine workers, meet in small buildings or discrete prayer rooms. But every demand for a proper house of worship awakens nervousness here.