The magnetic properties of nanostructures supported on metallic surfaces are of great interest, both because of the possibilities of atomic engineering of future spintronic devices, as well as due to the fact that such systems challenge our understanding of magnetism in general. Here, our research on the magnetic properties of nano-sized objects adsorbed on different substrates will be reviewed. Such theoretical investigations were performed using DFT (Density Functional Theory) based method, which is appropriate to treat complex magnetic structures [1]. From nanowires to corrals, we have explored the possibility of the occurrence of novel magnetic behaviors. A systematic study of the occurrence of noncollinear magnetism is presented, by changing the geometry of the supported nanostructures, where intriguing noncollinear magnetic ordering were obtained for Mn nanostructures adsorbed on Pt(111) [2], Fe(001) and W(001) surfaces. In particular, for Mn corrals on Pt(111) surfaces we identified a nano¬object presenting very complex stable magnetic configurations, which can be described by topological structures, as Skyrmions, in analogy to Z2 vortex¬like structures [2]. Also, for Mn nanostructures on Fe(001) the effect of spin-orbit coupling lead to the possibility of half skyrmion. Concerning metallic nanowires of Mn on W(001), we show the possibility of realizing complex noncollinear magnetic structures such as helical spin spiral. [1] A. Bergman, L. Nordström, A. B. Klautau, S. Frota¬Pessôa and O. Eriksson, Phys. Rev. B 73, 174434 (2006); Phys. Rev. B 75, 224425 (2007). [2] M. S. Ribeiro, G. B. Corrêa Jr., A. Bergman, L. Nordström, O. Eriksson, and A. B. Klautau, Phys. Rev. B 83, 014406 (2011).