Castello della Valle (Fiumefreddo Castle), founded in 1201, was the residence of the noble lords. During the mid-16th-century, the castle was donated to Ferdinando De Alarçon-Mendoza, marquis of the Valle, and took its current name of Castello della Valle. The current appearance dates from that age. The castle was besieged in 1806-1807 by French troops and nearly destroyed. Today it houses several works of local painter Salvatore Fiume.
Frösöstenen is the northern-most raised runestone in the world and Jämtland's only runestone. It originally stood at the tip of ferry terminal on the sound between the island of Frösön and Östersund. The stone dates to between 1030 and 1050. It has now been relocated to the lawn in front of the local county seat due to the construction of a new bridge, between 1969 and 1971, on the original site.
Frösö runestone inscription means: Austmaðr, Guðfastr's son, had this stone raised and this bridge built and Christianized Jämtland. Ásbjörn built the bridge. Trjónn and Steinn carved these runes.