There was a time, not all that long ago, when he was the invisible man whose name was a battle cry, his appearance known to most people only from an out-of-date photograph, a hidden hero on a prison island off the coast of Africa.

But as he celebrated his 90th birthday Friday, Nelson Mandela was anything but invisible, a figure of reverence whose nine decades have been marked and observed at a huge rock concert in Hyde Park in London, a gala dinner for his children's charity in the august, chandeliered Long Room at Lord's cricket ground, and a host of tributes.

His birthday celebration was supposed to be a quiet affair in his ancestral village, Qunu, in the southeast of his country - with a mere 500 of his closest friends in attendance, as well as a touch of wry self-deprecation: