Cover Story: Inside The Gates Foundation; With $36bn and a move to brand new premises early next year, the Bill & Melinda Gates Foundation is convinced of the value of its 'high risk, high return' approach. But can it crack some of the worst problems in global health and development? Gideon Rachman pays a rare visit to the organisation

The Bill & Melinda Gates Foundation is the richest private foundation in the world. It has ambitions to save millions of lives, to eradicate killer diseases and to wage war [...]