  (abridged) The old Star Cluster (SC) systems surrounding any sofar
investigated galaxy represent a powerful tool for the understanding of the
cosmological evolution of their host galaxies. Phases of enhanced cluster
formation can be identified by reliably age dating the clusters. These are
symptoms of violent star formation, results of intense starbursts as commonly
seen in merging nearby galaxies and high-z forming galaxies. However, the young
SC systems of nearby merging galaxies and the old SC systems of nearby passive
galaxies (most likely resulting from high-z starburst events of these galaxies)
appear to be significantly different in terms of their mass functions. Whether
this difference originates in differences in the formation physics/environment
or is only due to dynamical evolution of the cluster systems is currently a hot
issue. A main diagnostic for the survival probability of a newly formed cluster
is most likely its compactness, since less compact, fluffy clusters are more
vulnerable to destructive interactions with the galactic environment of the
cluster. For these reasons, we developed
  1) a tool to significantly improve photometry of nearby SCs (which appear
resolved on high-resolution images, provided e.g. by HST), by accurately
measuring and taking the cluster size into account, and
  2) a tool to effectively determine ages and masses (plus metallicities and
extinctions) of SCs from multi-wavelength photometry, ranging from the UV to
the NIR.
