New Delhi, April 7 President Pranab Mukherjee and Prime Minister Narendra Modi on Tuesday praised the Aga Khan for the work done by his foundation towards sanitation, heritage conservation and rural development. India appreciates the valuable contribution of the Aga Khan Development Network (AKDN) in restoration and heritage conservation, Mukherjee said after Prince Karim Aga Khan called on him at the Rashtrapati Bhawan, an official release said here.