Why has there been a surge of interest since September 11?
Sunday 4 July was American Independence Day, and a 20 ton block of granite was lowered into place at Ground Zero in New York. It's inscribed with a tribute to the people who died on September 11 2001 and will be the cornerstone of the building that will replace the World Trade Centre.
Since the destruction of the twin towers there's been a keen interest in America in the study of Islam, copies of the Koran are said to be flying out of book shops and significant numbers of Americans, particularly women, are said to be converting to the faith.
Sam Hardie met a group of converts in San Francisco to find out more.
