St. Martin and St. Nicholas Cathedral (), or simply known as Bydgoszcz Cathedral, is a Catholic church built in the 15th century. It has a Gothic style, serves as a parish church and cathedral of the Diocese of Bydgoszcz. It also houses a shrine dedicated to the Virgin Mary. Its address is 10 Farna Street.

It is the most valuable architectural monument of the Old Town, standing on the Brda riverside. It was elevated to cathedral on March 25, 2004, by decision of then Pope John Paul II. Since November 3, 1960, the cathedral has been registered on the Kuyavian-Pomeranian heritage list.

History Construction of the first temple The Bydgoszcz parish church was founded by first mayors of the city, Jan Kiesselhuth and Konrad, at the same time the parish itself was created, after Bydgoszcz's establishment in 1346. The church building and its adjoining cemetery (active until 1809) were located in the north-western corner of city marketplace (today's Old Market Place – ), reaching the banks of the river Brda and its millrace branches feeding water mills (today's Mill Island).

The 17th-century chronicle of Bydgoszcz by Wojciech Łochowski as well as historical researches suggest that prior the construction of the parish church, an older temple dedicated to Saint Giles had already been standing in the suburbs of the old city of Kujawski. From the 13th century, it served as a chapel of ease for local officials and knights of Bydgoszcz castle. After the construction of the castle in Bydgoszcz in the middle of the 14th century, Saint Giles's church replaced the castle chapel. Until building completion of the parish church, its priest resided at the chapel of ease. This episode established a later but distorted tradition, making Saint Giles's church the oldest parish church in Bydgoszcz; the chapel was demolished in 1879 when constructing Bernardyńska Street.

It is believed that Bydgoszcz parish church was partly a wooden church, and completed around 1364, before the erection of the first Carmelite monastery in Bydgoszcz (1398). The first mention of a church priest was made on 22 July 1402, a reference to the church dates back to 1408 and the title of the parish church was quoted in a 1417 document. Together with the church a parish school was established.

Part of the church was built of brick, allowing the synod of the diocese of Włocławek to take place here in January 1425. In addition, the northern wall of the present church still bears brick traces of windows and a portal. In 1425, a fire destroyed some elements of the building, probably the wooden roof, while archived city documents were also lost during this disaster, according to Wojciech Łochowski's chronicles.

Construction of the Gothic temple (1425-1466) The reconstruction of the temple the same year (1425) comprised the enlargement of the main building and the construction of two aisles. Since builders integrated into the new building the northern brick wall from the previous temple, the church displays a chancel wider than the nave by almost 2 metres.

Like other mediaeval religious structures, the construction did not interrupt the liturgical services, as mentioned in 1449 in a document related to the erection of the Holy Trinity Church in the northern suburb of the city (at the location of today's Poor Clares' Church.

Funding for the project, albeit fluctuating, was mainly provided during the Thirteen Years' War (1454–66) against the Teutonic Order, when Bydgoszcz was frequently visited by Casimir IV Jagiellon, his retinue, high ranking clergy, crowds of dignitaries, knights, and by the Margrave of Brandenburg Frederick II or Eric II, Duke of Pomerania. Jan Kościelecki, local power broker and one of the major financial tycoons in Poland at the time (1457–1475), also contributed in a significant way.

The church exterior was completed in 1466: the same year, interior decoration began with the altars being set up: Virgin birth of Jesus altar in the northern aisle in 1466; Stanislaus of Szczepanów altar (1488); main altar realized by Poznań painter Wawrzyniec Stuler, ordered by Bydgoszcz parish priest Mikołaj in 1460.

In 1497, Krzesław Kurozwęcki, bishop of Włocławek, organized there a synod for clergy of Kujawy. For this occasion, the church received additional dedications, complementing the one from the 14th century to Saint Nicholas: it received as patron saints Martin of Tours, Adalbert of Prague and Stanislaus of Szczepanów. The celebration of these dedications was celebrated each year, on the first Sunday after St Bartholomew the Apostle day (i.e. August 24).

The area of the aisle and the chancel, around , was in 1466 the ninth largest parish church in the diocese of Włocławek, after: Gdańsk's St. Catherine's Church, St. Mary's Church, St. Jean's church, St. Pierre-St. Paul's church and St. Barbara's church; Puck parish church; Church of the Holy Cross in Tczew. Within Kujawy, only the St. Nicholas parish church in Inowroclaw was larger.

Expansion of the 16th-18th century

At the end of the 15th century, roofs were elevated, using pine wood, brought via the Brda river and chopped on the spot, the gable and the presbytery roofs were star-shaped and vaulted. At the same time, the church's southern steeple was attached to the main body.

From 1466 to 1617, three quadrangular chapels were erected and attached to the main body, while a fourth chapel was built at the location of the former presbytery entrance. In 1559, a turret carrying a light bell cast by master Andrzej was set up at the edge of the nave roof; another bell was suspended there in 1668. In 1702, it was replaced by a Baroque turret, covered with bronze. It still stands today: it is octagonal and has a roof lantern. A new bell was ordered for this realization from bellfounder Absalom Wittwerck from Gdańsk.

In 1585, a Gothic rectangular sacristy was erected, abutting the northern chancel wall: an inscription from 1585 was discovered after the Second World War beneath the plaster of the window sill. Between 1712 and 1745, part of the wooden barrel vault ceiling between the two storeys was replaced by a lunette. In the 1650s, major construction and renovation works started: the tower received a third storey, as one can see today; a mannerist-style porch was built adjacent to the west façade, with an open vestibule in the basement; the western part of the timber roof truss over the nave body was replaced after 1651, according to dendrochronological research, including the repair of the tower stairs.

Under the chancel floor were six vaulted burial crypts: Two were realized in the eastern part of the north aisle, under the altars of the Virgin Mary and St. Lawrence of Rome; The other four were matched with the foundations of the four chapels.

Between 1712 and 1745, the whitewashed walls of the sacristy, the chancel, the nave and the pillars between the naves were covered in some places with figural polychromes. Other decorative elements of the walls were tombstone epitaphs. Most altars and religious furniture from before the Polish partition were destroyed during the Napoleonic Wars.

Larger roof repairs also occurred at the end of the 17th century, after the destruction by the fire in 1684 of the abutting watermill: during the fire, the wind directed the flames to the northern façade of the church. It took 15 years to clean and repair this heavy damage. The catastrophe brought other diocesan parish priests, from 1712 to 1763, to write about the state of quasi-ruin of the temple and its associated buildings, which contrasted with the good condition of other city monasteries and conventual churches: the Carmelites, the Bernardines, the Jesuits. The church, however, survived in this poor position until the start of the partitions of Poland, although no major emergency investment was made.

18th-century buildings

By the 18th century many buildings were erected in the vicinity of the church. On the church cemetery premises stood: a chapel house; a stone statue of John Nepomucene realized in 1745; a vaulted crypt located near the church's northern aisle; a monolithic chapel and a brick mound in the shape of a crypt.

On the western side of the cemetery, on the area between today's tenement house at Przyrzecze street 2, and the memorial to the Virgin Mary Immaculate Conception of Lourdes, stood a series of buildings comprising the Bydgoszcz parish school building and three houses inhabited by the vicar, his helpers and secular representatives of the church staff. The rectory was located on the eastern edge of the municipal necropolis, on today's Ks. Tadeusza Skarbka-Malczewskiego street.

Partition period (1772-1920) At the time of the incorporation of Bydgoszcz/Bromberg into the Kingdom of Prussia as a result of the Partitions of Poland, the parish church was indeed in a poor technical condition. In 1794, for the needs of the Kościuszko Uprising, the silver decoration was depleted, as well as numerous valuables, for a total of 256 grzywna. Other city monasteries also donated to support the revolt, like the Jesuits and the Bernardines.

At the beginning of the 19th century, the church was nearly a ruin. During the period of the Duchy of Warsaw (1807–1815), Russian armed forces used it for military purposes: most of the side altars and removable elements were destroyed at that time.

Between 1819 and 1829, the Kingdom of Prussia funded a refurbishment of the building. During the works, part of the religious equipment was stolen and three side chapels were demolished; the chapel on the northern wall (St. Fabian and Saint Sebastian) survived. Only three old altars were preserved (Blessed Virgin Mary, Saint Barbara, St. Fabian and St. Sebastian), some altars were taken from the other monasteries of the city, liquidated by Prussian authorities: two side altars – Saint Roch and Saint Anthony of Padua – from the Bernardine Church (17th to 18th century); two side altars – Our Lady of the Scapular and Saint Joseph – from the Carmelite church (17th to 18th century); a rococo picture of Carmelite brother Stanisław and four stalls with 18 seats were also taken over from the Carmelites church in Bydgoszcz. The renovated temple was eventually re-opened in 1831 and reconsecrated. In addition, before 1875, a neo-Gothic annex was erected on the spot of the former chapel of Saint Stephen.

During the Partition period, the temple was the only parish church in the city where the religious and national feeling was still alive among the Poles, especially during the Kulturkampf period.

Interwar period

After the incorporation of Bydgoszcz into the Second Polish Republic's territory in 1920, the parish was divided into five smaller ones, relieving the church of many of the faithful, who had grown to too great a number for the one church: in 1924 the parish comprised 100 thousand people. From 1922 to 1926, the church interiors were completely restored, on the initiative of the then parish priest, Father Tadeusz Skarbek-Malczewski: walls and vaults were covered with polychrome motifs executed by Henryk Jackowski-Nostitz, on a design by Stefan Cybichowski (1923–1924); stained glass was installed; on the main altar, a meticulous restoration of the Virgin Mary with the Rose was carried out.

Second World War