We report on three-dimensional Monte Carlo simulations of dilute solutions of multiblock copolymers made of regularly spaced hydrophobic and hydrophilic blocks in the limit of long chains with a large number of blocks. Using a lattice model we investigate the effects of the ratio of hydrophobic to hydrophilic block lengths and impact of the quality of the solvent on the intramolecular structure of the copolymers. In poor solvent and for given block lengths the simulations show evidence for the existence of different kinds of intramolecular self-assemblies depending on solvent quality: Micelles, chains of micelles, tubes, and layered structures are revealed by both statistical properties and visualization. The form factor signature of the different structures has been identified and is discussed in connection with its experimental observability. The existence region of the different conformations in terms of energy and entropy is summarized in a phase diagram.