In 1947, before matriculating at university, he spent two months working under Gunnar Ekelund as an archaeological field surveyor in Östergötland.
[1] When Ambrosiani graduated in 1952, he began work with the Riksantikvarieämbetet (Swedish National Heritage Board), including a stint at the Statens historiska museum.
[1] The next year he returned to Darsgärde, and following that, he led excavations in southern Sweden on behalf of the Riksantikvarieämbetet's Department of Ancient Monuments.
"[1] Ambrosiani soon became the head of the Excavation Departement at the Swedish National Heritage Board, filling the role from 1959 until 1974.
[2] Starting in 1990 and through 1995, Ambrosiani was also the project manager for the excavations at Birka, a Viking Age trading center.