Papers from session C75, Archaeologists without Boundaries: Towards a History of International Archaeological Congresses (1866-2006) presented at the XV UISPP World Congress (Lisbon, 4-9 September 2006) / Actes du XV Congres Mondial (Lisbonne, 4-9 Septembre 2006). Contents: 1) Establishing Prehistory. The Foundation of the International Congress (1865/1866) (Marc-Antoine Kaeser); 2) The 15th Congres international d'Anthropologie et d'Archeologie prehistorique (Portugal, 1930) (Ana Cristina Martins); 3) A Portrait of Floris Romer in the frame of Budapest-Lisbon CIAAPs 1876 - 1880 Congresses (Erzsebet Marton); 4) The International Congress of Prehistoric Anthropology and Archaeology and German Archaeology (Ulrike Sommer);"