Driven by antiferromagnetic quantum fluctuations on a deformable lattice, spin-Peierls systems dimerize magnetically and structurally at low temperatures. In this dimer phase all excitations with non-zero magnetization have a finite energy. The energy gain by a finite induced magnetization overcomes the energy gap at a critical magnetic field strength H-c. Above H-c, an incommensurately modulated magnetic and distortive domain wall pattern is formed. The magnetic modulation pattern and the low-energy excitation spectrum in this high-field phase of the inorganic spin-Peierls compound CuGeO3 are fully determined by elastic and inelastic neutron scattering and discussed together with theoretical predictions as well as other experimental results.