The hierarchical assembly history of our Milky Way galaxy has now been reconstructed in considerable detail, thanks to a combination of kinematic and chemical evidence from Gaia and other surveys. As impressive as these results are, the Milky Way remains just one galaxy - how can we generalise  these results to other galaxies? How typical is the Milky Way? Even in the era of 30-40 m class telescopes, detailed studies of individual stars in galaxies beyond the Local Group will remain challenging, but I will argue that stellar clusters can play an important role as tracers of the early assembly histories of external galaxies. Interesting results have already emerged over the past decade from studies of Local Group GCs, including evidence of accretion in the M33 GC system and the discovery of the extremely metal-poor cluster EXT8 in M31. Future spectroscopic surveys with instruments such as the MOSAIC spectrograph on the ELT, following up on imaging by Euclid, Roman, and other ground- and space-based facilities, promise to enable such work on a much grander scale. A recurring theme in the talk is the importance of serendipitous discoveries, of which several examples will be discussed: such entirely unexpected results often turn out to be no less valuable than those for which a particular programme may have been planned and designed.