Padise Monastery was a former Cistercian monastery. It was founded in 1310 by the dispossessed monks of Dünamünde Abbey in Latvia. King Eric VI of Denmark gave them permission to build a fortified monastery in Padise, where they moved in 1310, although construction of the stone buildings did not begin until 1317.
By 1343, at the time of the St. George's Night Uprising, when it was still only partly built, the monastery was burnt down and 28 monks, lay brothers and German vassals were killed. Rebuilding began in 1370. By 1445 all major works, including the construction of the gatehouse and the residential and service buildings, had been completed, and vaulting had been added to the church roof. The consecration of the main building took place in 1448.
Around the year 1400 Padise monastery had acquired extensive estates in Estonia and also in southern Finland and throughout the 15th century enjoyed a period of great prosperity and influence as one of the most important spiritual centres of Estonia. It began however to sell off its lands and entered a period of decline in the beginning 16th century. Nevertheless it survived the upheavals of the Reformation in the 1520s.
In the Livonian War, the last Master of the Livonian Order, Gotthard Kettler, fearing after the invasion of the Russians that the Swedes would occupy the monastery, occupied it himself in 1558, and in 1559 dissolved it, ejecting the monks and confiscating the buildings and estates. He converted the monastery itself into a fortress, which the Swedes duly took in 1561. In 1576 the Russians besieged and took it, and during their occupation strengthened the fortifications, but four years later were in their turn besieged by the returning Swedes, who regained it in 1580 after a long siege and a damaging bombardment.
In 1622 King Gustavus Adolphus of Sweden gave the estates of the former Padise monastery to Thomas Ramm, Burgermeister of Riga, in the possession of whose family it remained until 1919. Ramm converted the premises into a Baroque country house. When in 1766 it was struck by lightning and burnt down, the Ramms used the stone to build a Neo-Classical manor house nearby.
The remaining buildings, which were stabilised in the 1930s, are now used as a museum. A comprehensive restoration of the former monastery complex was agreed in 2001.
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.