The fascinating advances in single atom/molecule manipulations with the STM-tip allow scientists to fabricate artificial atomic scale structures, to study local quantum phenomena or to probe physical and chemical properties of matter at single atom and molecule level on crystal surfaces.@footnote 1-4@ The STM-tip is not only used as an imaging tool but also as a manipulating and even, as an engineering tool in these experiments. In this presentation, our recent results of single atom/molecule manipulation experiments conducted by using a low temperature UHV-STM on metallic surfaces will be presented. A variety of cutting-edge STM single atom/molecule manipulation procedures, in combination with complementary tunneling spectroscopy and imaging, are systematically used to develop robust and innovative experimental schemes. Using these schemes, we examine the mechanical stability, electronic properties and chemical reactivity of single molecules at the spatial limit. The presentation will include vibrational spectroscopy/microscopy of single sexi-phenyl molecules, electronic spectroscopy examinations of single Ag atoms/vacancies and self-assembled molecular films. Determination of mechanical strengths and internal conformational changes of large single molecules using tip-molecule interaction forces will be shown. Detail single atom movement mechanisms during quantum corral constructions with the STM-tip will be demonstrated. The extraction of single atoms from the native substrate and construction of various atomic scale structures on an atom-by-atom basis using the STM-tip will be presented by showing STM movies. @FootnoteText@@footnote 1@S.-W. Hla, K.-H. Rieder, Ann. Rev. Phys. Chem. 54, 307-330 (2003). @footnote 2@H.C. Manoharan, C.P. Lutz, D.M. Eigler, Nature 403, 512-515 (2000). @footnote 3@B.C. Stipe, M.A. Rezaei, W. Ho, Science 280, 1732-1735 (1998). @footnote 4@C. Joachim, K. Gimzewski, A.Aviram, Nature 408, 541-548 (2000).