Hochjuvalt Castle consists of two sections, the upper castle on a rocky spur above the valley and the lower castle along the trade road on the valley floor. The spur created a natural pinch point in the valley, forcing traffic from the Septimer, Splügen and San Bernardino Passes to pass through the customs post in the lower castle. The von Juvalt family first appears in records in 1140 and the castle is first mentioned in 1149. The von Juvalt family were vassals of the Bishop of Chur and had estates from Feldis/Veulden to Scharans. Around 1250 they built Innerjuvalt Castle about 2 km south-east of Hochjuvalt to improve their control over the area.
By the 14th century the castle passed, probably through inheritance, to the Rietberg family. Following the death of the last male heir, Johann von Reitberg, in 1349 the castle was supposed to pass to his relative, the Freiherr von Landenberg. However, the Bishop of Chur claimed Hochjuvalt as well as other Reitberg estates in the region. In 1352 the Bishop forced the Landenbergs to sign away their claims to the castle. Another claimant, the Freiherr of Lumbrein agreed to drop his claims for 250 gulden. Over the following century, the Bishops used the castle and its estates as collateral for loans from a number of wealthy families. In 1451 a war broke out between the residents of the Schams valley and Counts of Werdenberg-Sargans. Several castles in the area were partially destroyed in the war, though it is unknown if Hochjuvalt was one of them. It was last granted to Eberhard Ringg von Baldenstein in 1454, though its condition was not recorded. By 1500 the castle was completely abandoned and around 1550 was described as a ruin.
During World War II the site was reoccupied and fortified. In 1940 guns were emplaced near the old upper castle and tank barriers were added around the lower.
In 2011-12 the castle was reinforced and repaired and a new foot path was added to the upper castle.
The oldest part of the castle is the residence tower high above the valley. Most of three sides of the tower have collapsed, leaving an 'L' shaped five story wall still standing. The castle was surrounded by a ring wall that probably enclosed the entire top of the spur. Today only a few traces of this wall remain. The castle was protected by two ditches on the mountain side of the spur.
The lower castle stretches between the base of the spur and the river banks. There are three doors in the wall, one toward Chur, one toward the Viamala road and one toward the Rhine river. Inside the wall, the only remaining building is a 9 m × 9 m tower in the south-west corner. The foundations of a similar tower are visible in north-west corner.References:
Ängsö Castle was first named as "Engsev" in a royal charter by king Canute I of Sweden (r. 1167-1196), in which he stated that he had inherited the property after his father Eric IX of Sweden. Until 1272, it was owned by the Riseberga Abbey, and then taken over by Gregers Birgersson.
From 1475 until 1710, it was owned by the Sparre family. The current castle was built as a fortress by riksråd Bengt Fadersson Sparre in the 1480s. In 1522, Ängsö Castle was taken after a siege by king Gustav Vasa, since its owner, Fadersson's son Knut Bengtsson, sided with Christian II of Denmark. However, in 1538 it was given by the king to Bengtsson's daughter Hillevi Knutsdotter, who was married to Arvid Trolle.
In 1710, the castle was taken over by Carl Piper and Christina Piper. Ängsö Castle was owned by the Piper family from 1710 until 1971, and is now owned by the Westmanna foundation. The castle building itself was made into a museum in 1959 and was made a listed building in 1965. It is currently opened to visitors during the summers.
The castle is a cubical building in four stores made by stone and bricks. The lower parts is preserved from the middle ages. It was redecorated and expanded in the 1630s. The 4th storey as well as the roof is from the expansion of Carl Hårleman from 1740-41. It gained its current appearance in the 1740s.