We report on low-energy beam deposition of Aun clusters on atomically flat Au(111) terraces epitaxially grown on mica. Cluster beams were produced by a laser-vaporization source. The size distribution was derived from time of flight mass spectrometry, and typically ranges from the monomer up to hundreds of atoms. Scanning tunneling microscopy (STM) of the deposited clusters yields information on the cluster shape and stability upon impact, and on cluster coagulation. The distribution of the cluster heights as observed by STM indicates an epitaxial growth of the clusters on the Au(111) surface. Scanning tunneling spectroscopy (STS) at low temperatures allows us to identify quantum size effects in individual Aun clusters. The size effects become apparent in the conductance spectra as pronounced and sharp peaks.