20 years ago, from July 8 to 20, 1990, 60 researchers gathered for two weeks at Castillo-Palacio Magalia in Las Navas del Marques (Avila Province, Spain) to discuss cognitive and linguistic aspects of geographic space. This meeting was the start of successful research on cognitive issues in geographic information science, produced an edited book (D. M. Mark and A. U. Frank, Eds., 1991, Cognitive and Linguistic Aspects of Geographic Space. NATO ASI Series D: Behavioural and Social Sciences 63. Kluwer, Dordrecht/Boston/London), and led to a biannual conference (COSIT), a refereed journal...