Rosersberg Palace is a 17th-century Baroque palace from the height of the Swedish Empire, later used as a summer residence by Charles XIV John. Its museum is strongest in summer, when guided tours show rooms with unusually well-preserved original textile furnishings.
The palace also holds an early replica of the United States Declaration of Independence, given by the United States in 1801. Together with the lakeside setting, it makes a worthwhile excursion from Sigtuna.