I: Theories with Torsion -- Generalities on Geometric Theories of Gravitation -- Four Lectures on Poincaré Gauge Field Theory -- The Macroscopic Limit of the Poincaré Gauge Field Theory of Gravitation -- QuasiClassical Limit of the Dirac Equation and the Equivalence Principle in the Riemann-Cartan Geometry -- Contracted Bianchi Identities and Conservation Laws in Poincaré Gauge Theories of Gravity -- The Gauge Symmetries of Gravitation -- The Motion of Test-Particles in Non-Riemannian Space-Time -- Torsion and Strong Gravity in The Realm of Elementary Particles and Cosmological Physics -- III: Supersymmetries, Twistors and Other Symmetry Groups -- The Fading World Point -- Superalgebras, Supergroups, and Geometric Gauging -- Four Lectures at the 1979 Erice School on Spin, Torsion, Rotation, and Supergravity -- Self Dual Fields -- An Introduction to Complex Manifolds -- A Brief Outline of Twistor Theory -- III: Experimental Relativity and Other Topics -- Experimental Gravitation with Measurements Made from Within a Planetary System -- Tests of General Relativity at the Quantum Level -- The Mass-Angular Momentum-Diagram of Astronomical Objects -- Bimetric General Relativity Theory -- Covariance and Quantum Physics-Need for a New Foundation of Quantum Theory? -- Relativistic Equations of Motion of "Spin Particles" -- Angular Momentum of Isolated Systems in General Relativity -- Isometries and General Solutions of Non-Linear Equations -- On the Visual Geometry of Spinors and Twistors -- Gravitation Photoproduction in Static Electromagnetic Fields and Some Astrophysical Applications -- Invariant Deduction of the Gravitational Equations from the Principle of Hamilton -- On a Generalization of the Notion of Reimann Curvature and Spaces with Torsion -- Comments on the Paper by Elie Cartan: Sur une Generalisation de la Notion de Courbure de Riemann et les Espaces a Torsion.