US President Barack Obama took a walk alone on the Great Wall on Wednesday, wrapping up a visit to China with a visit to the ancient fortifications that symbolise the country's history and separateness.
"It's magical. It reminds you of the sweep of history," Obama said, after breaking away from his tour guides to walk alone along the snowy parapets, hands jammed into his pockets against the cold and wind.
"It gives you a good perspective on a lot of the day-to-day things. They don't amount to much in the scope of history."
Many Chinese see the Great Wall as a symbol of the power of their civilisation. To many outsiders, it stands for the insularity and barriers thrown up by the Middle Kingdom.
In 1972, Richard Nixon broke through the barriers of the Cold War and visited China on an equally cold and clear day.
"My hope is that in the future, perhaps as a result of the beginning that we have made on this journey, that many, many Americans... will have an opportunity to come here," Nixon said in 1972, at the same steep, curving Badaling section of the wall.
Nixon hoped "that they will think back as I think back to the history of this great people, and that they will have an opportunity, as we have had an opportunity, to know the Chinese people, and know them better".
Ties between the U.S. and China have grown so much since that the two economies are now deeply intertwined, while the U.S. must accommodate China's growing influence on the world stage.
The Obama trip did not yield immediate breakthroughs on the many issues the two giant economies face, foremost among them currency and protectionism. But it did keep the lines of dialogue open and was accompanied by profusions of friendship.
"Our time here on Earth is not that long and we better make the best of it," Obama said at the Wall, before heading off to South Korea, the final leg of his Asia trip.