There is sometimes a wistful note in Barack Obama's voice when he speaks in public these days. The US president makes regular references to his "remaining time in office" and notes that there are just two and a half years to finish the work that will define his legacy. That legacy will find a physical home in his presidential library, the museum-archives America's leaders build after leaving office to stand as a testament to their time as the world's most powerful man.
Mr Obama's library is still years from completion but every step in its planning process serves as another reminder that his presidency is reaching the beginning of its end. Monday is the deadline for cities to submit their proposals to be a host site for what will one day be known as the Barack Obama Presidential Library.