A survey of the nanometrology-related activities in progress at the Istituto di Metrologia “G. Colonnetti” (IMGC) is presented. Some special apparatus for critical measurements in the nanoscale range are described. The development of instrumentation and methods for quantitative scanning probe microscopy, optical diffractometry, and atomic scale displacement metrology by combined x-ray and optical interferometry is outlined. Focus is given on calibration and methods for traceable measurements, high-resolution positioning, and subnanometer displacements measurements.