A century after the publication of “Catalogue of the land mammals of western Europe” (1912), Gerrit Smith Miller’s contributions to European mammalogy endure. His work was a landmark treatment of the European fauna and laid the groundwork for subsequent mammalogists. Miller’s impressive body of specimen-based research underscores the fundamental role natural history collections have played in building our understanding of the natural world. Their relevance to basic discovery endures, as collections have evolved since Miller’s time to include new materials (e.g., tissues, cell suspensions, linked host/parasites), and as new tools (e.g., genomic sequencing, stable isotopes, niche envelopes) for extracting information have developed exponentially. While still utilized for systematic and taxonomic questions, museums and associated web-based databases (GBIF, GenBank, GoogleEarth) are now critical to our ability to rigorously address questions related to environmental change (e.g., climate change, habitat conversion, emerging pathogens, pollutants and toxicants, biodiversity loss, introduction of exotics). Specimens are the primary resource that objectively documents diversity and vouchers historic conditions. By representing a particular site and time, georeferenced specimens establish critical baseline conditions against which temporal change can be investigated. As in Miller’s day, museums remain centers for research and training as future generations of scientists are introduced to biodiversity studies.