The present paper is devoted to the problem of the so-called pseudo-polygonal vaults in the Gothic architecture, which might be regarded as one of the most striking examples of the medieval architectural illusionism. As a pseudo-polygonal vault such a rib construction is understood, that evokes an impression of a polygonal wall termination in a rectangular interior, usually a choir. The most important distinctive feature of the pseudo-polygonal vault is a tripartite composition of at least one internal elevation; besides, there are two basic types of such coverings. The older one, which originated in the early 12^th century in Normandy (church of Saint-Étienne, Caen), is characterized with a radial arrangement of the ribs, which are supported in all the four points of the eastern wall. The second one emerged for the first time in the West-French region of Anjou in the last decades of the 12^th century (entrance porch of the former Benedictine abbey at Saint-Florent-lès-Saumur), and is characteristic for the triangle corner fields, usually filled with bisectional ribs. St. James’ parish church in the New Town of Toruń in North Poland is described and analyzed here as the most perfect example of the pseudo-polygonal choir arrangement, in which all the architectural details are planned in a way to emphasize the seeming multi-sided termination of the chancel. The church is presented here in the broader background of the North-European brick Gothic architecture, and the Hamburg, Rostock and Lochstedt influences are traced and explained. The paper’s main goal is to introduce the pseudo-polygonal vaults to a broader range of art historians, thanks to the splendid example of St. James’ in Toruń.