The study aims to draw attention on a visual document from the eighteenth century held by the Austrian State Archives in Vienna, which reveals information about the former Franciscan church of Târgu Mureş, prior to its Baroque transformation (1790-1791). In question is a plan record of the town castle, drawn up in 1772 by Paul Schmidt, a local master mason originating from Bavaria, which renders the former Franciscan convent in Târgu Mureş. Of particular interest is the church ground plan, which contains a row of four pillars in the middle of the nave revealing a structure with two vessels, so far unknown. After the Franciscan friars were expelled in 1556, the church sustained serious damage during the 1601 siege of General Basta and the 1658 fights of George II Rákóczi for the princely throne of Transylvania, then again in 1704, when the city was burned down during the kuruc war (1702-1711). In 1693 the church suffered a renovation with the support of Michael Teleki, the nave being covered with a timber ceiling of which only two panels have survived and are exposed today on the north wall of the choir. The existence of a double-nave hall church is proved by written sources as well, such as the account of local pastor Gábor Nemes, who testified that originally the nave’s ceiling had been sustained by pillars that were torn down during the 1790-91 renovation carried out by Paul Schmidt’s disciple, Anton Türk. The premise of a medieval hall type structure was supported in the 1920’s by conservator László Debreczeni, who has estimated the construction of the church in the fourteenth and fifteenth centuries and assumed that the ship was originally covered with ribbed vaults. The main argument in favor of a vaulted Gothic nave would be the presence of pier buttresses along the side walls. Churches with two vessels of equal width divided by a row of pillars aligned in the axis of the choir represent an uncommon type of medieval religious buildings in Transylvania, at least in the light of current knowledge. The only building of this kind was the parish church in Baia Mare, now vanished, which is known from visual documents of the nineteenth century and recently confirmed by archaeological excavations. The Transylvanian heritage also counts three examples of churches with two asymmetrical vessels i.e. Bonţida Reformed Church (Cluj county), the Lutheran Church of Lechinţa (Bistriţa-Năsăud county) and the Franciscan Church of Sibiu (vanished). Regions relatively close to Transylvania, where the double-nave plan spread in the fourteenth century, include southern Poland (Wiślica, Stopnica, St. Stephen Krakow), Bohemia (Třeboň, Bavarov, Soběslav, Selčan), the former Upper Hungary (Lubica, Velká, Spišská Belá) and Austria (Imbach, Dürnstein, Pöllauberg, Enns Wallsee Chapel). The Franciscan churches with double-nave plan from these regions (Levoča, Košice, Vienna, and Enns) may have influenced the introduction of this type of building at Târgu Mureş Franciscan church. Nevertheless, in this latter case the question of building chronology, i.e. if the central pillars were dating back to the Gothic phase or were introduced later, during the 1693 renovation, is still waiting an answer. The final answer may be provided only by archeological investigation, however, the information from written accounts and the 1772 plan record point to a Hall church with two naves as a building phase to be considered in the history of the monument.