Enormous pockets of oil, gas and minerals are believed to lie hidden deep beneath the African continent's surface. But these riches have so far brought relatively little benefit to Africans. The International Monetary Fund labels twenty countries in Sub-Saharan Africa as "resource-rich". But the IMF's sister organisation, the World Bank, says these countries have often sold their concessions too cheaply.
The Bank says the lack of reliable information about what the resources are actually worth is part of the problem. It has launched a project called the Billion Dollar Map to help. Our team in Washington went to the global headquarters of the World Bank to find out more.