Pope Benedict is in Spain for a Catholic youth festival that has sparked protests because of its high cost.

Spain's king and queen greeted the pope as he arrived at the airport in the capital, Madrid, Thursday. A throng of young people waving Vatican flags also was there to welcome him.

More than one million young Catholics from around the world were expected to pour into Madrid ahead of the pope's arrival.

Highlights of the World Youth Day celebration include a mass confession and prayer vigil Saturday in the presence of the pope and a celebration of Mass on Sunday morning.

The pope also will meet with Spanish Prime Minister Jose Luis Rodriguez Zapatero, whose government has promoted several policies opposed by the church, including relaxing Spain's divorce laws, easing restrictions on abortion, legalizing same-sex marriage and allowing gay couples to adopt children.

This is the Pope's third visit to Spain since his election in 2005, but it comes at a time when the nation's economy is faltering. Bitter debates have erupted over the visit's estimated $72 million cost and the Catholic Church's role in Spanish politics.

Riot police in Madrid clashed with demonstrators Wednesday on the eve of the pope's arrival. Thousands marched through the streets, shouting critical slogans.

Spanish daily newspaper El Pais reported eight people arrested and 11 others hurt in the street violence.

Criticism of the four-day papal visit has come mainly from the “Indignant Ones” protest movement, which has been protesting the country's economic woes, government spending cuts and 21 percent unemployment.

On Tuesday, Spanish police arrested a Mexican chemistry student who was allegedly planning to attack those protesting the Pope's visit. Authorities say he was planning to use asphyxiating gases and other chemical substances.