The Semedo site is one of the oldest archaeological sites in Indonesia, and the discovery of fossils and artifacts dates back thousands of years. The existence of this site is vital as it provides valuable insights into the life and culture of prehistoric humans in the Nusantara. This significance led to the establishment the Semedo Archeological Site Museum, which aims to preserve and store these findings. This study aimed to: first, analyze the history and development of the Semedo Archeological Site Museum; second, describe the collection of the Semedo Ancient Site Museum; and third, analyze the efforts made by the museum, the community, and the government in preserving fossils and antiquities. This study utilized historical research methods consisting of the following stages: (1) Heuristics (the stage of searching for and collecting data sources). (2) Critique, which is divided into two types: external critique (criticism of the authenticity of sources) and internal critique (criticism of the credibility of data sources). (3) Interpretation and synthesis (interpretation of information from data sources). (4) Historiography (writing history). The study revealed: (1) History and Development: The museum was established based on requests from fossil discovery pioneers. Construction began in 2015, and it was officially opened in 2022. The museum has complete buildings and facilities. (2) Museum Collection: The Semedo Ancient Site Museum's collection included land fauna fossils, marine fauna fossils, and antiquities discovered at various locations in the Semedo site by fossil discovery pioneers, the Semedo community, and archaeologists. (3) Preservation Efforts: Fossil and antiquities preservation efforts were carried out by various parties, including museum managers, the Semedo community, visitors, and the government.