Hazrat Abdullah Shah Ghazi (RA) is the patron Saint of Karachi. People, most of them Muslims, come here to pay homage to him from across the country. His tomb is built on a very high platform, but people say that his actual grave is downstairs. I recommend it because I think you cannnot understand the life in Pakistan without understanding these 'mazars' (tombs). They are a micro version of any city where they exist.
It is at Ghizri, Clifton. Ask any taxi driver and he will take you there.
Is this your business?