  We have visualised and studied vortex configurations in mesoscopic
superconducting disks using the Bitter decoration technique. For a broad range
of vorticities L the circular geometry is found to result in the formation of
concentric shells of vortices. From images obtained on disks of different sizes
in a range of magnetic fields we were able to trace the evolution of vortex
states and identify stable and metastable configurations. Furthermore,
quantitative analysis of shell filling with increasing L allowed us to identify
'magic' numbers corresponding to the appearance of consecutive new shells.
