For hundreds of years, the castle was the seat, residence and administrative center of the Archbishop of Nidaros.

The Archbishops of Nidaros expanded the castle gradually, with great halls and residential areas being built over time.

Norway's last Archbishop, Olav Engelbrektsson, attempted to make a final stand and defend the castle during the Reformation but eventually fled into exile.

[1] After the abolishment of Roman Catholicism, the castle became royal property where the local lensherre resided.

The castle was restored, rebuilt into a residential palace and eventually used more for military purposes, again being expanded considerably.