At the last major event of his 26-hour visit, the German pope presided at a mass for what organisers said was about a million people on the grounds of a sprawling futuristic arts and science complex in Spain's third largest city.

In his homily to the crowd, the pope, wearing green and white vestments, several times praised the traditional family, founded on "indissoluble marriage between a man and a woman."

The Spanish royal family attended the mass but Prime Minister Jose Luis Rodriguez Zapatero did not. His government has clashed head-on with the Church over several issues, mainly last year's legalization of gay marriage.