This introductory article of the special issue of Acta geographica Slovenica on old maps examines the importance of old maps as the foundation and culmination of geographical research. Maps, one of the earliest languages of communication, have guided exploration and become reference documents. Old maps reveal history, values, and contexts of geographical regions and geographical science. They serve as a special form of text, making possible communication across centuries. Old maps have inspired fantasy maps that depict fictional landscapes and create a cultural phenomenon. This special issue contains articles that analyze the cartographic elements of old maps, the semiotics of old maps, their use in education, and their historical significance, as well as an article on the first Slovenian atlas. Old maps challenge geographic knowledge and representation, and they are shaping the digital future.