The church of Saints James and St Nicholas was established as a Franciscan monastery church. A site near the Market Square, at the current Biskupia street, was assigned for the construction of the monastery and the church. Having powerful protectors, the Franciscans could afford to manifest a magnificent temple and a spacious monastery. They have been building the construction since the twenties of the 14th century for almost 100 years. The temple was consecrated around 1346 by bishop Otton.
The Chełmno Franciscan convent broke up in the era of the Reformation. In 1539 there were no monks in the monastery, and bishop Tydeman Giese gave the buildings temporarily for the needs of the townspeople. The Franciscans reappeared in Chełmno around 1582, expanding the convent throughout the 17th century. The first Partition of Poland in 1772 was a tremendous shock for the monastery. On the special order of Prussian king Frederick Wilhelm III in 1806, the process of cassation of the Chełmno monastery begun.
Work on the construction of the church was carried out in two stages. First, a temple was built with an equal height of naves and chancel. It was only during the later reconstruction that the central nave was raised to the height of 21.3 meters, giving the temple a pseudobasilica form. Also, the length of the chancel was extended by 8 meters, that is of one span, so that it would match its length with the naves. Finally, a three-nave building was erected on a rectangular plan with a narrower, rectangular presbytery on the eastern side and a four-sided, higher octagonal tower on the south side. The length of the interior was 49 meters, the width of the naves 16 meters, and the chancel 9.6 meters. From the north monastery buildings were adjoining to the church.
The naves were decorated with beautiful stellar vaults, while in the chancel, vaulted much earlier, a simple groin arrangement was used, decorated with unique bosses. The huge 621 m² temple vault was rested on four massive pillars, and its weight was distributed via ancillary columns to the perimeter walls, which were not only 1,4 meters thick, but were also supported by fifteen buttresses. However, the interior does not make an overwhelming impression. You can feel the harmony resulting from the symmetry and above all, the lightness of this architecture. This impression was achieved by ripping the plane of the walls with great thirteen windows. It was not until the final stage that the western gable was added, which raises into the sky at a height of 42,4 m. An octagonal, slender bell tower is even higher. It measures together with the crowning cross up to 54,5 m.
During the painting works in the interior of the temple in 2006-2007, on the walls of the chancel and the nave, under a thin layer of paint, beautiful medieval figural paintings were discovered, probably coming from the turn of the fourteenth and fifteenth centuries.
Webpage odznaka.kuj-pom.bydgoszcz.pttk.pl, Kościół p.w. śś Jakuba i Mikołaja w Chełmnie.
Webpage wikipedia.org, Kościół św. Jakuba i św. Mikołaja w Chełmnie.