There are only a few mathematicians in the history whose works and questions are still intensively studied after 150 years by many people in the original form and are continuing to provide inspiration to generations to come. Bernhard Riemann (1826-1866) is one such mathematician.

According to Narasimhan in a preface to Riemann's Collected Works,``Great mathematicians change the way their successors look at certain parts of mathematics. It is rare, however, that a hundred years after a man's work, his ideas and methods are learnt and used by people in the field in essentially the same form in which he left them. Riemann's mathematics has this quality of permanence to an astonishing degree. His work has been analyzed, amplified and generalized in many ways in many fields, but a good part of his mathematical output has withstood the test of time and the search for new perspectives remarkably well. This is not to imply that new perspectives have not been found but simply that in many instances, Riemann's own approach has not been superseded definitely."

Each generation of mathematicians need to read Riemann and to understand and interpret his work. To help the mathematics community to understand better the work of Riemann and its impact, Prof. S.T. Yau and several of us are launching one book project with the title: The legacy of Bernhard Riemann after one hundred and fifty years. It will consist of systematic contributions by leading experts around the world on subjects or topics influenced by Riemann.