Castle of the Teutonic Knights - Taking advantage of the marshy terrain of the Nida valley the Teutonic Knights built a wooden guard castle on the hill. The first mention of it was made in 1376. The fortification extension resulting in one of the biggest single-wing residential and fortified castle was completed about 1400.
It became a seat of the Order commander and it was to protect numerous villages established by the Order in the region of Dąbrówno, Olsztynek and Działdowo against retaliatory campaigns of the Lithuanians. At the beginning of the 16th century the castle was converted and the approaches of the castle were equipped in 1517 with surrounding walls and a bastile on a circular plan adapted to firearms. In its history the fortification was besieged several times. In the 19th century the castle was seriously destroyed by the troops stationing here. The fortress was saved from the total devastation by a court counsellor of Nidzica, Ferdynand Tymoteusz Gregorovius. Thanks to him the castle was reconstructed in 1830 and used as a seat of offices, private apartments as well as a prison. In 1945 a part of the castle rooms were burnt down. In 1965 the magnificence of the castle was restored together with its former decor.
Small Monastery - It dates back to the end of 14th century. It is a gothic fortified structure. It was located in the south-eastern corner of the town and was an element of the town fortifications. Originally its eastern part played a role of a corner tower. Later it was used as a school for lower rank church staff, barracks, a town library and a cinema. Before burning down in 1914 it was used as a granary. It was destroyed in 1945. After reconstruction in the years 1967 - 1988 it was adapted to become a branch of the State Archives in Olsztyn.
Saint Adalbert's Church - It was constructed in 14th century and was included in the town fortification system in the western part of the town. A fragment of the fortifications have been preserved till today and it can be seen at the entrance to the presbytery of the catholic parish from the church side. The first mention of the church is found in the town foundation charter from 1381. A ceremonial consecration took place in 1404. In 1664 as a result of fire the church was burnt down and reconstructed again. Then it was converted in the 18th century and burnt down again in 1804. In 1807 the French turned it into a field bakery. For 12 years till the reconstruction time church services were conducted in the town hall room. As a result of war operation it was burnt down again. It was reconstructed in the years 1920 - 1924 when it was given the pseudo-Renaissance style that has been preserved till today.
Saint Cross's Lutheran Church of the Augsburg Confession - It was built in the years 1858 - 1860 in the neo-Gothic style whereas a tower was added in 1890. The walls were made of stone hewn out of erratic blocks and bound by bricks. A wooden ceiling is made of ceiling coffers. The internal decor constitutes a collection of valuable sacred art monuments from the territory of the southern Mazury region.
Most of all they include wooden old altar paintings (the oldest ones from the 15th century) and wooden sculptures coming from the former evangelical churches. The modern sacred art is represented by three paintings by an outstanding painter, Hieronim Skurpski.
Former Brewery - It was established in 1868 and originally it was named ‘Schlossbrauerei Neidenburg' (Nidzica Castle Brewery). In 1902 it was transformed into a partnership and it has remained the only operating brewery in Nidzica (there were three of them). Then it was the best brewery in the neighbourhood and its output amounted even to 25 thousand hectolitres annually.
The 2nd World War did not stop the brewery operation. It provided employment to 44 people. After the war it housed an orangeade bottling plant and after the refurbishment in 1958 the Nidzica Wine and Mead Factory was established that was famous for its excellent meads. Upon the decision of the Provincial Conservation Officer the former ‘Castle Brewery' was entered in 1992 in the national register of historic monuments as an interesting example of the 19th century industrial architecture. At present it is privately owned and has the following name: Wine and Mead Factory in Nidzica.
Town Hall - It was built in 1842 in the place of the previous one pulled down in 1824. It represents the neo-Classical style. At present it is a seat of the Town Hall offices in Nidzica, the Tourist Information Centre, a weekly ‘Voice of Nidzica; and also the ‘Nida' Nidzica Development Foundation.
Remains of the town ramparts - Currently a seat of a company store of a mobile network operator and the Tower housing the Sanitary and Epidemiological Station.
Manor and park complex in Zagrzewo - It is a former landed estate and even knight's lands. It might have been also endowment by the Order for the service under its banners. It is known that the estate had numerous owners. The Franckenstein family were the last owners till 1945. The buildings well preserved till today include the whole manor and park complex together with outbuildings and houses of the manor employees. It was build at the beginning of our century in the neo-Baroque style. Fortunately it has not been converted. Today it is privately owned. The park surrounding the manor was designed by a son of Johann Larass, Ernst at the time when the manor was built. There are numerous species of old trees preserved. An ancient big maple with its unique form is a pride of the park.
Church dedicated to the Exaltation of the Holy Cross in Kanigowo - Built in the 15th century of stone on a rectangular plan, the western wooden gable with a turret. Completely refurbished in the 18th century.
Church dedicated to the Holy Heart of the Blessed Virgin Mary in Łyna - Originally wooden, existed already in the pre-Reformation period. In the years 1725 - 1726 a new church was built on a rectangular plan, room type, made of stone blocks. It has a three-side roof. Completely renovated in 1771.
Church dedicated to Saint Andrzej Bobola in Żelazno - The date of erecting the fist church is unknown but it is known that it existed already in the pre Reformation period, It was burnt down in 1656 during war operations. A new wooden temple was built only in 1721 and it survived till 1857 when due to its poor technical condition it was disassembled. A new church built on a rectangular plan, room-type, with a gable roof, was erected in 1880 of hewn field stones and bricks. It has survived till today.
Łyński Mill - Built at the beginning of the Łyna river course. The first mentions of it date back to 1387. After water damming a small lake of the area of 1 ha was created. A bother of the Order of Teutonic Knights, namely a commander Johann von Baffart from Ostróda was the first mill owner in 1387. Originally the mill served for grinding flour and then it was adapted for processing of groats. In 1657 the mill outbuildings were used by drapers from Nidzica as a fullery (for cloth production) with water-driven presses. In the same year both the mill and the fullery were burnt down and thirteen years later reconstructed by the same drapers. In 1782 Friedrich Augustyn became an owner of the Łyński Mill and in 1820 it was inherited by his son Arthur. Kollwitz was the last owner. During the 1st World Was the mill was occupied by the Russians. During the 2nd World War it was used as a prison. After the war the mill was operating for several more years.
Swedish Rampart - Between the villages of Zimna Woda and Wały you can encounter a longitudinal rampart. It is named the Swedish Rampart. Currently it is 3.2-kilometre long. It is an early medieval fortification at the Mazovian and Prussian border that has been well preserved till today. The found ceramic material makes it possible to assume that it must have been built by the Mazovia inhabitants at the turn of the 10th and 11th centuries protecting themselves against invasions of the Prussians or maybe also against invasions of the Lithuanians going after the Teutonic Knights. It linked Czarne Lake with the drained marshes to the Orzyc River and Omulew Lake. The decision regarding the construction of the fortification in this place was taken also on the basis of the lie of the land. The fortification was closing an entrance to the traffic corridor in a place where the route running from Prussia turned to the south after crossing a narrowing between the Jastrzębie Mountains and Czarne Lake. The bypassing of this fortification was impossible due to the marshes and lake. The Swedish Rampart is entered in the national register of the ‘0' class historic monuments of the Warmińsko-Mazurskie Province
source www.nidzica.pl