Trondheim, historically Kaupangen, Nidaros, and Trondhjem, is a city and municipality in Trøndelag county, Norway. As of 2025, it had a population of 216,518. Trondheim is the third most populous municipality in Norway, and is the fourth largest urban area.

Trondheim lies on the south shore of Trondheim Fjord at the mouth of the River Nidelva. Among the significant technology-oriented institutions headquartered in Trondheim are the Norwegian University of Science and Technology (NTNU), the Foundation for Scientific and Industrial Research (SINTEF), the Geological Survey of Norway (NGU), and St. Olavs University Hospital.