Berlin and Washington are bound by a deep friendship. It developed in the Cold War and has now survived more recent turmoil in transatlantic relations.
The casual question from the old man he'd just been having such a nice conversation with hit him like a slap in the face. "What country are you from?" Juan Diaz was outraged. The memory of the anger that boiled in him still twists up the corners of his mouth. How dare he! When he'd tried so hard to speak his best German? Then Juan Diaz smiles - the man gave him a hug, just like that, when he told him he was from America. "And he said: I remember the Americans saving my life when I was a little kid. With the Berlin Luftbrücke [Berlin airlift].' "
In the summer of 1948, Soviet troops had cut West Berlin off from the outside world, and for almost a year, US and British planes brought supplies to the city's people. A lump comes to Juan Diaz' throat when he remembers the hug. He has to sniff and blink away tears before he can continue - since that day he has stopped keeping his nationality a secret.
Mark Hallerberg understands why Juan Diaz might have wanted to keep his citizenship to himself. During George W. Bush's presidency, it wasn't always easy to be an American in Europe.
The economics professor at the Hertie School of Governance in Berlin knows compatriots who preferred to pretend they were Canadian so that they wouldn't have to contend with criticism of their country's foreign policy, particularly the decision to invade Iraq against the will of many allies, including Germany. Being an American meant taking the blame.
"It severely damaged the respect that the US traditionally enjoyed in Germany," says Hallerberg. The relationship improved with the election of Barack Obama, "but in Berlin it was a little easier even before then, because of the special history," he adds.
After the war, American troops guaranteed the city's security, especially when Cold War divisions were cemented with the construction of the Berlin Wall in 1961. "The people were scared," says Alina Heinze, director of the small Kennedy Museum in central Berlin, which documents the US president's life up to his death in 1963.
She points to a small black-and-white photo showing thousands of people crowded onto a square, reduced to tiny dots. They were all there to see John F. Kennedy, who made a speech from the Schöneberg district town hall on June 26, 1963, which promised support for West Berlin with the immortal words, "Ich bin ein Berliner."
People often forget that Kennedy was on a nationwide trip that took in a number of other German towns, points out Heinze, but the visit to the divided city and its Wall overshadowed all the rest - especially since it came two years after its construction and in the middle of one of the "tensest phases of the Cold War."
From protector to partner
Even today, older Berliners occasionally cry when they remember those times, Heinze says. They talk about the sense of trust that Kennedy's visit gave them, the hope that Washington and US troops would stand by them against the Soviet East.
As she tells the story, Heinze carefully locks up the room where a special exhibition is to document Kennedy's visit over the coming months. The captions on the photos aren't finished yet. "Today the relationship between America and Berlin is very different, of course," she says. It is more of a "partnership of equals." After the reunification of Germany in 1990, Berlin no longer needed the protection, and US soldiers were withdrawn from the city.
Or at least most of them were: a few blocks from the Kennedy Museum, a US flag can be seen flying in the breeze. Next to it stands a well-tanned soldier, staring at the crowds of tourists gathering at Checkpoint Charlie, the former crossing point between East and West Berlin.
A woman stands next to him, beams into her husband's camera, and holds two fingers up in the air as a victory sign. Is he really an American? The soldier's response to the question is an irritated shrug. The next group of tourists is waiting to have its photo taken - he's there to make money, not to clear up questions of national identity.
"The de-romanticization of German-American relations" is how Johannes Thimm, senior research associate at the German Institute for International and Security Affairs (SWP), sums up transatlantic relations since the end of the Cold War. In the past few years, Washington has re-orientated itself elsewhere, mainly toward Asia, he argues.
He adds that while a lot of German politicians are worried that Germany is no longer important to the US, he is more relaxed on the issue. He basically sees the re-orientation towards Asia as proof that Europe has been a success story - an area where there are no major crises that the US needs to intervene in.
Special treatment for Americans?
Economically, and especially culturally, relations between the US and Europe are already much closer than with other regions. More than 100,000 Americans live in Germany, almost 15,000 of them in Berlin, and the tendency is upwards. People like Stephanie Hausotter, who came to Berlin to do a master's degree and then stayed after she met her future husband.
Now Stephanie works in a small private college in Berlin. A few years ago she was living near the US Army base in Frankfurt, where she sometimes tuned in to the army radio station. "An odd, but really nice feeling to hear American voices and music and the top 40 countdown on a German radio frequency," she said. "It was an interesting reminder of the American presence in Germany." While in Frankfurt she often felt like an outsider, in Berlin she always feels welcome, she said.
So can Berlin be home to an American? Juan Diaz nods as he sips his organic elderberry lemonade, much loved in the trendy Prenzlauer Berg district where he lives. He became a naturalized citizen a few years ago, and now has two passports. He thinks he was favored in the language test he had to pass to gain citizenship. After it was over, the woman who gave the test chatted with him for nearly an hour. "She said, 'because it's so nice to talk to Americans.' " Somehow the special treatment bothered him.