Pope Benedict XVI has arrived in Turkey on his first trip to a mainly Muslim country since acceding to the papacy.
The Pope said Turkey was a religious bridge
Prime Minister Recep Tayyip Erdogan met him at Ankara airport and they had a 20-minute meeting, despite earlier claims Mr Erdogan would not have time.
The meeting was clearly intended to calm tensions and set a positive tone for the visit, correspondents say.
The visit has been overshadowed by anger among many Muslims, enraged by comments the Pontiff made about Islam.
Tens of thousands protested on the streets of Istanbul at the weekend, calling on the Pope to stay away or apologise for his remarks.
Security is tight, with 15,000 police on guard. Snipers are in place and a decoy motorcade will be used during the four-day visit.
Turkey says security will be higher than for US President George W Bush's visit in 2004 - but officials insist he will not be in danger during his trip.
The trip was arranged in part so the Pope could meet the spiritual leader of the Orthodox Christian Church, in Istanbul.
In Ankara, the Pope began his trip with a visit to the hilltop mausoleum of modern Turkey's founder Mustafa Kemal Ataturk.
Flanked by an escort of ceremonial guards, he laid a wreath of red and white flowers.
While in Turkey, Benedict will become only the second pontiff to visit a mosque, and will also meet Islamic and Jewish leaders as well as the heads of Turkey's Christian communities.
The Pope told the prime minister he wanted to visit Turkey because it was a bridge between religions and cultures.
"I want to reiterate the solidarity between the cultures," he said. "This is our duty."
During his airport meeting with Mr Erdogan, the pontiff gave Turkey support for its bid to enter the European Union, the prime minister said.
28 Nov: Arrives in Ankara, meets PM Recep Tayyip ErdoganVisits mausoleum of Mustafa Kemal Ataturk, founder of modern republicMeets President Ahmet Necdet Sezer
29 Nov: Goes to Ephesus to celebrate mass at site where Virgin Mary believed to have died Goes to Istanbul to meet Patriarch Bartholomew I, spiritual leader of the Orthodox Church, for first of series of encounters
1 Dec: Visits Haghia Sophia (6th Century Byzantine church converted into mosque in 1453, then transformed into museum in 1935) and Blue Mosque
Correspondents say that with membership negotiations on a knife-edge, there is extreme sensitivity about the attitude of the Christian West towards Turkey - and the Pope's visit may be a focus for those concerns.
Opposition to Benedict's visit also stems from comments the Pope made during a trip to Germany in September.
In a speech to an academic audience, the Pope quoted a Byzantine emperor who characterised Islam as a violent religion.
While the Pope insisted the remarks did not reflect his own views, the speech was widely reported and caused anger across the Islamic world.
Ahead of the Pope's arrival, one government minister said he hoped the papal visit could become a "turning point" in relations between Christianity and Islam.
"What our guest says, what he does and will do is important," said Justice Minister Cemil Cicek.
In 1981 a Turkish gunman, Ali Agca, wounded Benedict's predecessor, Pope John Paul II, in a Rome shooting.
Popes Paul VI and John Paul II visited Turkey in 1967 and 1979, respectively.