Situated picturesquely on Lake Siesiki , the castle, or rather chateau , is an example of a Renaissance residence, which , although it no longer performed strictly defensive functions, still used the architectural language of medieval fortresses . In this way, the building accentuated the chivalry of its owners, the Dowmont-Siesickis , who, according to family legend, descended from the Lithuanian prince Gediminas.

No scholarly study has yet been written about the picturesque castle, or rather chateau, in Siesiki, but authors of historical novels like to situate the action within its walls, as exemplified by "Emilia Plater" by Wacław Gąsiorowski. The castle itself, with the peculiar charm of its thick and squat walls, has become the stuff of legends , and there are many fatuous stories about it in various guidebooks. First of all, it should be noted that a small defensive point must have existed here as late as the 15th century. , at the time of King Władysław Warneńczyk (1434-1444), the eldest son of Władysław Jagiełło. At that time, the wooden and earthen structure belonged to Dowmont (Dowmunt) , the "Duke of Ucian". It served not only as a watchtower, but also as a starting point for hunting in the surrounding, then dense Lithuanian forests.

At the beginning of the 16th century, the owner of the Siesiki estate was a descendant of Dowmont - Gabriel Dowmont , who built a walled residence on the shores of the lake by 1517 . He and his successors were called Dowmont-Siesicki of the Bawola Head coat of arms from the name of the village. They were active participants in political life in the Wiłkomierski district, but did not gain much importance. Their most prominent representative was Kazimierz Władysław (d. 1691) - Marshal of the Lithuanian Tribunal in 1676 and Grand Master of Lithuania, Elector of Jan III Sobieski.

In the centuries that followed, various modernisation works were undertaken at the castle , and the estate remained in the hands of the Dowmont-Siesickis until the beginning of the 18th century , when Marianna (Marcjanna), a Mstislav voivode, married Michał Antoni Radziwiłł (1687-1721) of the Trąby coat of arms. After the heirless death of her brothers Casimir and Stanislaus, she brought the Siesiki estate into her husband's household. Their son-in-law, Leon Radziwiłł (1722-1751 ) , sold the indebted estate to the Dowgiałłos of the Zadora coat of arms in 1745 . However, the memory of the Dowmuntas survived in the names of the nearby villages of Dowmuntyszki and Dowmuntowo.

The new owner, Kazimierz Dowigiałło, rebuilt the palace, which had been destroyed by the Swedish army during the Swedish invasion. Another restoration in 1820-1839 was carried out by his grandson Dominik (1789-1857). Among other things, he had the towers on the lake side crowned with a neo-Gothic crenellation and the two front towers demolished. A classicist stable and granary were also built at this time. The next owner was Stanislaw Grzegorz Dowgiałło (1822-1905) . It was on his initiative that a neo-classical building called the Academy was built nearby in 1904 , to serve the visitors and school purposes of the local people. The building has two porticoes organised on its shorter sides.

The Dowgiałło estate remained in the hands of the Dow giałło family until 1940 , when Oskar Jan Dowgiałło (1902-1988) and his wife Krystyna, née Jezierska, were forced to leave it. After the war, they settled in Sopot. After 1945, a school was placed in the palace, followed by the offices of the kolkhoz and flats for its workers. From 1972 the building was abandoned. In 1999, renovation began, which was completed a few years ago by placing a branch of the museum in Vilkomir in the palace.

The castle was built over a lake and surrounded on three sides by a moat. It is an elongated rectangular building, two-storeyed, originally framed in four corners by squat towers, one storey higher than the main body. Only two of these have survived, on the lake side - one on a circular plan and the other on a quadrangular plan. This suggests that they were not built at one time. In the following decades, a terrace was extended between the towers, allowing visitors to admire the picturesque surroundings, but also to look over the owner's property stretching to the horizon. The building is crowned by a high roof. The body of the building, with its various projections of the towers, decorated with arcades, panels and alternating openings, was characterised by its picturesqueness. The castle in Sišiai can be compared with similar watchtowers in Lithuanian Rokanciškės or Narviliškės.

Old fireplaces and vaults from the 16th-18th centuries have been preserved in the Sišičiai Castle, as well as the polychrome and brick floor. Some of the rooms were covered with ceilings. The castle-residence was surrounded by a 3 ha park, the remains of which are still visible today.