A direct descendant of the Prophet Mohammed, the Aga Khan is well known globally for his philanthropic works aimed at improving people’s lives.

The Aga Khan, who became the spiritual leader of the world’s millions of Ismaili Muslims at age 20 as a Harvard undergraduate and poured a material empire built on billions of dollars in tithes into building homes,

Ceremonies were being held Tuesday in Ismaili communities in the U.S. and others were held elsewhere in the world Wednesday.