The Portuguese built Fort Jesus in 1593. The site chosen was a coral ridge at the entrance to the harbor. The Fort was designed by an Italian Architect and Engineer, Joao, Batista Cairato. The earliest known plan of the Fort is in a manuscript Atlas by Manuel Godinho de Heredia – dated 1610 which shows the original layout of the buildings inside the Fort.
It was built to secure the safety of Portuguese living on the East Coast of Africa.