Due to their fundamental character and experimental difficulties, measurements of electric and magnetic form-factor of the neutron are of paramount importance to hadron physics. Particularly rich information can be obtained from momentum-dependence of the form-factors as it reflects the underlying electromagnetic structure of the nucleon. The electric form-factor of the neutron is the most poorly known. To determine it accurately, a profound understanding of the deuteron and the 3He nucleus (which serve as effective neutron targets) is also needed. The form-factors were measured at the MAMI accelerator facility (Mainz, Germany). The measurement of the electric form-factor of the neutron was performed in the region of its largest sensitivity, at four-momentum transfers of 0.14 and 0.25 GeV2. At the same facility, the first pilot experiment on double-polarized virtual Compton scattering was performed as well. The results of this experiment will open a new possibility to extract some of the previously unknown components of generalized polarizabilities of the nucleon. The measurements of pion electroproduction close to threshold are important as tests of chiral perturbation theory, which so far is the only satisfactory approximation to quantum chromodynamics at low energies. On the other hand, pion electroproduction in the region of the Delta resonance enable us to probe the quadrupole deformation of the nucleon which can be inferred from measurements of interferences between the quadrupole electric and Coulomb amplitudes with the magnetic dipole amplitude. The low-energy experiment were performed at MAMI (extracted the axial form-factor of the nucleon), while the N to Delta experiment was performed at Jefferson Laboratory (Newport News, USA). In the latter facility we have also measured double-polarized elastic scattering on protons, from which the ratio of electric and magnetic form-factors of the proton could be determined in a previously inaccessible kinematic region. The surprising result that the form-factor ratio drops to almost 1/2 at Q2 approaching 6 GeV2 has already stirred an extended discussion of possible two-photon contributions to the process which have so far not been accounted for. The knowledge on heavy nuclei and inter-hadronic interactions, which we have accumulated in our research of the structure of heavy hadronic systems, is one of the basic building blocks in a deeper understanding of the structure of matter. We have obtained new results on nuclear structure in the vicinity of doubly-magic closed shells from a new measurement on 98Cd. In the iThemba Laboratory (Cape Town, SAR) we have acquired new data on the 208Pb(p,gamma) reaction which is of great relevance in astrophysics (stellar energy, synthesis of heavy elements). We have succeeded in increasing the energy resolution in high-energy gamma ray detection by roughly an order of magnitude. The new results have also confirmed with great certainty the consistent direct-semidirect model which was also developed within our group.