Ninety years ago, in November 1929, the Jesuit Fathers of the Pontifical Biblical Institute started their excavations at the site of Teleilat Ghassul on the eastern bank of the Jordan river, just north of the Dead Sea. If the initial impetus was the search for Sodom and Gomorrah, part of contemporary debates among scholars on their location, the expedition uncovered what remains one of the major sites for the Chalcolithic. Over several seasons of excavation (1929-1938, 1959-60), the expedition left a legacy of archaeological material, now mostly in the collection of the Museum of the Pontifical Biblical Institute in Jerusalem, as well as significant archival material: plans and sections, glass plate negative and photo albums, pottery registration cards, finds registers as well as excavation diaries, providing interesting insights into their developing excavations methods and the result achieved.