Gravitational lensing -- The general relativistic N-body problem -- Observable relativistic effects in the solar system -- New results for relativistic parameters from the analysis of llr measurements -- Very-Long-Baseline Interferometry in astro-, geo-, and gravitational physics -- A gradiometer experiment to detect the gravitomagnetic field of the earth -- The international atomic time and the PTB's clocks -- Gravity-wave astrophysics -- The GEO-project a long-baseline laser interferometer for the detection of gravitational waves -- The optics of an interferometric gravitational-wave antenna -- Mechanical aspects in interferometric gravity wave detectors -- Fermion and Boson stars -- Black holes with hair -- Gravitational fields of rapidly rotating neutron stars: Theoretical foundation -- Gravitational fields of rapidly rotating neutron stars: Numerical results -- A new laboratory experiment for testing Newton's gravitational law -- Matter wave interferometry and why quantum objects are fundamental for establishing a gravitational theory.