The Cambridge University Herbarium has a rich history of over 300 years of plant collection, inventory, production of taxonomic literature, and teaching of botany. The herbarium of some 1.1 million dried, pressed plant specimens includes collections made by some of the great British botanists including Charles Darwin, Alfred Russel Wallace, Nathaniel Wallich, and Richard Spruce. Over its history, the Herbarium has experienced various stages of evolution, expansion, changing research focuses, and threats, and over the last 100 years was particularly important in European and British taxonomy and floristics. Currently the collections are relatively poorly known and have virtually no visibility outside the physical building in which they are housed. The historic specimens represent a treasure trove of unstudied material and are especially rich in nomenclatural type specimens. This paper aims to provide an overview of the history of the collection, and to raise awareness of its existence. Now with a new Curator, in an era of collections digitisation and interdisciplinary research, the potential to open this Herbarium up via collaborative research, teaching, and engagement is huge.