The United Kingdom's National Archives is sharing an incredible collection of well over 1,000 photos from England's colonial office. You may find it at this address: http://www.nationalarchives.gov.uk/africa/
Beginning in the 1860s and stretching forward well into the 20th century, the pictures show the beauty of Africa's people and geography, as well as hinting (at the very least) at some of the tensions inherent in the colonial enterprise. Nigeria has the largest number of photos (904), with South Africa coming in second (627), and Kenya third (346). A word of caution--exploring the collection can take up a lot of your time. But it will be worth it.