This volume is intended as an introduction to group-theoretic methods in analysis on spaces that possess certain amounts of mobility and symmetry. The focus is on the three topics in the subtitle. The introductory chapter deals with the three two-dimensional cases of constant curvature requiring only elementary methods and no Lie theory. Chapter I deals with modern integral geometry and Radon transforms. The second chapter deals with the interconnection between Lie groups and differential operators whereas Chapter V develops the theory of spherical functions on semisimple Lie groups with a certain degree of completeness. Each chapter concludes with "Exercises and Further Results" and solutions/references are provided at the end of the book.