A security guard walks past a montage of U.S. dollar bills outside a currency exchange bureau, ahead of a scheduled state visit by U.S. President Barack Obama, in Kenya's capital Nairobi July 23, 2015. Obama will land in Kenya on Friday with a mission to strengthen U.S. security and economic ties, but his personal connection to his father's birthplace will dominate a trip that Kenyans view as a native son returning home. REUTERS/Thomas Mukoya TPX IMAGES OF THE DAY