Trøndelag (Urban East Norwegian: [ˈtrœ̂ndəˌlɑːɡ]; or Trööndelage  is a county and coextensive with the Trøndelag region in the central part of Norway. It was created in 1687, then named Trondhjem County ; in 1804 the county was split into Nord-Trøndelag and Sør-Trøndelag by the King of Denmark-Norway, and the counties were reunited in 2018 after a vote of the two counties in 2016.

Trondheim, historically Kaupangen, Nidaros and Trondhjem, is a city and municipality in Trøndelag county, Norway. As of 2022, it had a population of 212,660. Trondheim is the third most populous municipality in Norway, and was 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.