In the late 12th century the lords of Hallwyl am Aabach established a small castle complex 700 metres from the run-off at the northern end of Lake Hallwil.
It consisted of a residential tower surrounded on three sides by a dry moat. Large boulders were placed at the outside of the tower walls, as is commonly found in castle towers in the region dating back to the same era or slightly later.
There was also an inn serving the castle residents which was presumably older than the castle itself.
As the Hallwyl family gradually grew in importance and reputation, the space afforded by the tower castle became too limited. This was remedied in around 1265 with the construction of the keep, which was erected directly on the bank of the stream east of the residential tower. Two rooms on the ground floor were used to store supplies. The first and second floors consisted of residential rooms.
A bridge was built over the Aabach, possibly around the time the keep was constructed if not some time previously.
Johans I of Hallwyl (1305–1348) resided in the castle in the first half of the 14th century. He had the tower castle extended to create a moated castle with dual fortifications.
In the marshes of the stream lowlands, an artificial island was banked up which had a curtain wall on three sides and was completely surrounded by moats. Newly erected features at this stage were the castle chapel, a wooden bakehouse and the circular tower which still stands today. After this, the Old Building was constructed: a large, two-storey residential edifice which was prestigious in character. The South Building - the predecessor to the Front Building - was also erected during this period.
When Aargau was conquered by the Confederation in 1415, the castle was set on fire by Bernese troops. All that remained was the residential tower and some rooms in the keep at the rear of the castle.
Reconstruction took several years and led directly to the extension of the complex. In around 1420/25 the keep was extended to the south on the rear island.
In around 1500, Dietrich of Hallwyl (1462–1509) had turrets (dungeon tower, archive tower) built at the eastern corners of the rear island which had thick walls, arrow loops and embrasures.
The Old Building was demolished in around 1520. Parts its walls were used to erect the granary that still stands today.
At around the same time, the three-storey western tract was added to the Front Building. The two-storey northern tract was then added to the keep on the rear island in the third quarter of the 16th century.
Burkhard III of Hallwyl (1535–1598) had extension work carried out from 1578 to 1590 to convert the castle into a manor house.
Stair towers were built, facades were reconstructed and the festive hall in the rear section of the castle took on the form in which it still exists today. The castle barn likewise dates back to this period.
A mill was mentioned for the first time in the 14th century. Today's mill building dates back to 1637 and occupies a third island directly to the north of the castle complex.
It consisted of a two-storey stone house with a gabled roof and was expanded in the 19th century. The grinding room was on the ground floor while the miller's residential quarters were on the upper floor. Today the grinding room with its three millstones is open to visitors as a museum. The modern building that replaced the former mill barn houses a transport ship dating back to the 16th century.
Having already had various conversions and refurbishments carried out in the 1860s, Hans Theodor of Hallwyl (1835–1909) had the Front Building, the gateway tower and the western tract redesigned in neo-Gothic style from 1871 to 1873.
When economic crisis forced him into bankruptcy in 1874, the interior decoration work was incomplete. Walther of Hallwyl acquired the family's ancestral home in order to preserve it.
After being purchased by Walter of Hallwyl (1839–1921), who lived in Stockholm, Hallwyl Castle remained unused for three decades. Walter of Hallwyl's wife Wilhelmina, née Kempe, initiated an archaeological investigation, and from 1910 to 1916, the castle complex was restored according to the most advanced principles of monument preservation known at the time, including removal of the neo-Gothic conversions.
Swedish archaeologist Nils Lithberg was commissioned to lead the excavations, while architect Anders Roland was entrusted with restoring the buildings.
After the death of her husband, Wilhelmina of Hallwyl (1844–1930) established the Hallwil Foundation in 1925. This trustee organisation took on responsibility for the castle complex and opened it to the public.
The castle museum
In 1994 the castle was endowed to the canton of Aargau. It was in urgent need of general restoration and this was carried out under the supervision of a broadly based building commission from 1997 to 2004. The foremost principle of construction work was to preserve the historical fabric of the buildings. Wherever interference with the floors and historical structures was unavoidable, the canton's archaeological specialists conducted excavations and investigations beforehand. As construction work progressed, planning and realisation of the museum got underway. The permanent exhibition now illustrates the history of the Hallwyl family and its relations with the Seetal valley.
Johans I (1305–1348) was a marshal, a guardian in Sundgau, and later a bailiff in Swabia and Alsace. He carried out important assignments for the Habsburg sovereigns and was the official educator of Duke Frederick.
He later used his position to expand his power in Aargau. Johans I is regarded as the most powerful and most successful member of the Hallwyl family. It was he who had the Hallwyl tower castle enlarged to create a prestigious castle complex.
Hans (1434–1504) had fought under the Habsburgs as well as under the Kings of Bohemia and Hungary.
On 22 June 1476 he led the Bernese troops to victory at Murten against Charles the Bold, Duke of Burgundy, and went down in history as the Hero of Murten.
Dietrich (1462–1509) established a farm and cultivated the land belonging to Hallwyl Castle himself.
He had a fish pond created in the Schlatt and maintained a sound income from the sale of carp.
Hartmann III (1503–1573) studied theology under Wolfgang Capito in Basel and later went to the universities of Mainz and Leipzig.
He welcomed Luther's revolutionary ideas, gave up his plans to become a priest and took up service as an envoy and emissary for the City of Bern. In 1546/47 he was an emissary of Bern in the Schmalkaldic War.Hartmann III (1503–1573) studied theology under Wolfgang Capito in Basel and later went to the universities of Mainz and Leipzig. He welcomed Luther's revolutionary ideas, gave up his plans to become a priest and took up service as an envoy and emissary for the City of Bern. In 1546/47 he was an emissary of Bern in the Schmalkaldic War.
Burkhard III (1533–1598) collected medical recipes, researched into his family's history and had several extensions and conversions carried out in Hallwyl Castle.
He owned an experimental laboratory with distillation apparatus and supplies of medicines similar to that of an apothecary. In around 1580 he compiled more than 2,500 recipes in the 'Hallweil Book of Medicines' including the 'Genuine Hallwyl Magic Potion'.
At the instigation of his father Dietrich, Johann Georg (1544–1604) obtained a sinecure at the cathedral chapter in Basel in 1579.
His training and his later period of office as bishop were influenced by the Jesuits: he was said to be strictly devout, eager for reform and unselfish. In 1601 he was unanimously voted bishop of the largest bishopric in the German-speaking region by the cathedral chapter of Constance.
Bernhardine, née Diesbach (1728–1779), came from a wealthy Bern family and married the 55-year-old Johannes of Hallwyl when she was aged 16.
After the latter's death, she suffered considerably due to the loss of her daughter, fear for her sick sons and her own infirmity.
Franziska Romana, née Hallwyl (1758–1836), married her cousin Abraham Johannes and was Lady of the Castle as a widow for more than 50 years.
Born into a period of upheaval, she witnessed the downfall of the Ancien Régime, the French Revolution and the foundation of the canton of Aargau. She followed all these developments with great interest.
Karl Franz Rudolf (1777–1852) served under the Russian Tsar and became a captain in the artillery battalion of the Imperial Guard.
After his return to Hallwyl Castle he was Lord of the Castle for 40 years, becoming a citizen and colonel of Aargau as well as being voted onto the Grand Council. The family lost many of its privileges in the aftermath of the Helvetic Revolution. Karl Franz Rudolf fought countless legal battles to defend his family's rights, causing him to amass considerable debt. In 1833 he was finally forced to sell the castle mill.
The wife of Walter of Hallwyl (1839–1921) was the daughter of a Swedish industrialist. During the course of her life she assembled an extensive collection of paintings, porcelain, silver, weapons and utility objects. These can be viewed by the public today at Hallwyl Museum in Stockholm.
Wilhelmina of Hallwyl (1844–1930) invested most of her large inheritance in the restoration and documentation of Hallwyl Castle from 1910 to 1916. After her husband's death she established the Hallwil Foundation in 1925. This trustee organisation took on responsibility for the castle complex and opened it to the public.