Trondheim is a small city, and most places can be reached by walking. However, if necessary, there are buses and taxis available to take you around. Bus rides cost 50 NOK for a single trip, while taxi prices vary depending on the destination.
If you have more time to spend in Trondheim, consider adding a day to explore the nearby Trondheim Fjord or the historic Bakklandet neighborhood. If you have less time, consider skipping either the Ringve Music Museum or the Trondheim Science Center and Planetarium to make the most of your day.