Nanostructures are investigated increasingly by ultra-high vacuum (UHV) electron microscopy in the last decades. In recent years scanning tunneling microscope (STM) and/or atomic force microscope (AFM) is incorporated in UHV electron microscope apparatus to study not only structures but also properties in-situ. Also a great advance in the optics of the electron microscope, aberration free lens, allows us to image individual atoms (or atomic columns) within nanostrucutres. I present recent development of our UHV high-resolution electron microscopy that has an aberration free lens and a scanning probe microscope, and results on conductance quantization of metal nanowires and forces acting on the free-standing nanowire that spans between electrodes