The lecture will offer a reminder, review and verification of alternative interpretations of what really happened on November 17, 1989. It will try to uncover and explain why such interpretations always - even after so many years - reappear. First of all, he will try to reconstruct what we really know about the events of November 17 and how to understand them (mainly by placing them in a broader factual and temporal context). Oldřich Tůma focuses on contemporary history: the history of Czechoslovakia after 1945, the history of the Cold War. His original research focus was on medieval and Byzantine history. After matriculation (1969) he studied history and philosophy at FFUK. In 1975, he was expelled from his studies for political reasons. He completed his studies remotely (1980; PhDr. 1982). PhD. at FSVUK 2007. After being expelled from studies, he worked in various non-academic jobs (laborer, assistant educator, archivist). At the same time, he devoted himself to research in the field of Byzantine history, occasionally publishing in foreign and domestic magazines. In 1989, he joined the then Institute of Classical Studies of the Czechoslovak Academy of Sciences full-time, with whose Byzantological department he had previously collaborated (e.g. incognito in the editorial office of the magazine Byzantinoslavica). In 1992, respectively In 1993, after returning from a study stay at the National Humanities Center in Research Triangle Park, North Carolina, he moved to the Institute for Contemporary History, where he was its director from 1998-2017. Oldřich Tůma was or is a member of domestic and foreign scientific bodies. Among other things: a member of the disciplinary councils of postgraduate studies at FSVUK or FFP of the University of Silesia; member of the editorial board of the magazines Contemporary History, Journal of Cold War History, Jahrbuch für historische Kommunisforschung; member of the scientific board of the European Network Remembrance and Solidarity or the Hannah Arendt Institute for Totalitarismusforschung at TU Dresden. He has been a member of the Scientific Council of the Academy of Sciences of the Czech Republic since 2017.