16 heartwarming photos of Barack Obama and Angela Merkel's friendship

As two of the world's most powerful individuals, it's only natural that the relationship between Chancellor Angela Merkel and President Barack Obama is one of the closest in politics.

Their friendship has been one of the few uplifting constants in a dramatically transformed world of politics.

But goodbyes are hard, and with president-elect Trump preparing to move into the White House, Obama has been carrying out his final international tour - and he made sure Germany and Merkel were on the itinerary.

ABC quotedDeputy National Security Advisor Ben Rhodes as saying:" They've worked together on almost every issue. They've developed a deep mutual respect, I think, and close friendship as well... He wanted to see Chancellor Merkel one more time to thank her for her partnership and leadership."

The pair tackled the global financial crisis, promoted free trade, and forged an international accord to fight climate change. But like all good things, their time working together must come to an end. We've gathered some of the best pictures of Merkel and Obama's time together.