US President Barack Obama arrived in Berlin on Tuesday for his first visit to the German capital as president, with the 24-hour trip's climax a speech before thousands at the iconic Brandenburg Gate, dpa reported.
After departing from the Group of Eight summit in Northern Ireland, Air Force One touched down at the city's Tegel Airport around 8 pm (1800 GMT).
The president, who is traveling with First Lady Michelle Obama and his two daughters, has no official engagements in the evening.
Obama is set to meet on Wednesday with German Chancellor Angela Merkel before his speech to an invitation-only crowd in the city's central Pariser Platz, in front of the Brandenburg Gate.
A dais and grandstands have been erected on the square, where the US embassy occupies one frontage. Officials have spoken of 4,000 vetted guests, but a newspaper, the Berliner Morgenpost, said the list expanded to 6,000 names after Washington gave the okay.
The address comes nearly 50 years after US president John F Kennedy's famous "Ich bin ein Berliner" speech.
While officials from both sides have emphasized in interviews the countries' historic friendship, Obama's visit comes as many Germans have voiced criticism over last week's revelations of the US government's telephone and internet data surveillance programmes.
Members of Germany's Digital Society Association rallied Tuesday at Checkpoint Charlie, a famous Cold War border crossing that has become a popular tourist attraction. One placard said, "Yes we scan" - an allusion to Obama's 2008 campaign slogan "Yes we can."
They charged that the US National Security Agency's electronic spy operations were a violation of human rights. Other outraged Germans have compared the NSA's tactics to the former East Germany's Ministry for State Security (Stasi).
During his first term, Obama twice visited parts of Germany distant from Berlin. However, in the language of diplomacy, it is his official visit to the capital that counts as a sign of friendship.
Obama's last visit to Berlin was in 2008 as the presidential candidate of the Democratic Party. He gave a campaign speech to a crowd of 200,000, with the city's Victory Column as a backdrop.
Both Washington and Berlin have played down the disclosures of the NSA's surveillance under the code-name PRISM. But Merkel has been urged by many politicians to demand that Obama explain the spying, which targets foreigners.
"The PRISM affair will undoubtedly overshadow Obama's visit," said Heike MacKerron, director of the Berlin office of the German Marshall Fund, in a briefing note.
"The real danger, though, is that the PRISM revelation may lead to greater distrust during the negotiations for a Transatlantic Trade and Investment Partnership (TTIP)," she said. That deal would ease trade barriers in public procurement and norms and standards.
Merkel had a close relationship with his predecessor, George W Bush, and reportedly took time to get used to Obama. German public opinion favoured Obama over Bush, but Germans have since cooled to him.
MacKerron said Germans fault Obama for: not bringing Washington behind an international climate change agreement; keeping the detention facility at Guantanamo Bay open; increasing the number of drones used in warfare; and failing to impose stricter gun control.
She said Obama would probably be pressing Germany at talks with Merkel to assist its weaker neighbours in overcoming the euro crisis.
"The view that Germany is selfishly wielding its clout - imposing austerity policies on weaker European economies in order to protect German taxpayers - can not only be heard in southern Europe, but also in Washington," she said.
Security was high for the visit, which ranks as an "official" one rather than a top-rated state visit.