The paper introduces new findings on the construction and furnishing of Plečnik's church of St Anthony in Belgrade, which are based on previously unconsidered archival material from Belgrade and Jajce. Aside from the parish chronicle, the plans, and other relevant material, this material also includes numerous letters from Plečnik to his Franciscan friend Josip Markušić, preserved at the Franciscan monastery in the Bosnian town of Jajce. As a provincial head, Markušić turned down the immature plan for the church, most likely the work of the same architect who built the monastery for the Franciscans in Belgrade two years prior. Priest fra Arkanđelo Grgić used his ecclesiastical connections to contact architect Jože Plečnik. At the beginning of 1929, the latter, without being familiar with the actual state of affairs, sent the Franciscans a sketch of a longitudinal church with a wide bell tower, reminiscent of his church in Prague. Furthermore, he offered them a less expensive alternative, a round church, which the Franciscans happily accepted. He planned the church with a high bell tower, a symbol of Catholicism in an orthodox environment, where the churches do not have bell towers. He replaced the originally planned dome with a flat ceiling as he did not trust the local masons' ability to build it, while it would also hugely exceed the financial resources of the order. After the foundations were finished, they had to decide between visible bricks or cheaper plaster. At the request of Plečnik, the Franciscans decided on visible bricks from a brick factory in Bečkerek that were almost three times more expensive. The construction of the church lasted two and a half years, and it took place during the time of the greatest economic crisis. The masons were Hungarians from Vojvodina. In its raw state, the church was completed in 1932. The works were overseen by retired architect Dušan Granić, who acted hastily and was arbitrarily responsible for some irreversible mistakes in many places. For example, at the request of the Ministry of Construction but without Plečnik's knowledge, he partially changed the foundations, because of which it was later impossible to construct a crypt. Even though Plečnik at first tried to find Serbian executants, he later entrusted the interior design to his renowned craftsmen from Ljubljana, with which Markušić, who succeed Grgić, agreed and wanted everything to be made under the architect's supervision. Regarding the altar and other equipment, Plečnik and Markušić carefully navigated between attractiveness to a wider circle of believers and high artistic quality. At the request of the Franciscans, Plečnik turned to Ivan Meštrović in regard to the statue of the patron of the church, however, he was not particularly satisfied with the work that was sent. A few months before his death, he recommended his assistant architect Janez Valentinčič to Markušić's successor fra Eduardo Žilić. Valentinčič completed some of the furnishings in the presbytery based on his teacher's plans, laid marble pavement, and built the entrance porch. He also finished the barely begun construction of the bell tower, and at the request of the Franciscans, used a reinforced concrete core with which he changed the bell tower's structure. [ABSTRACT FROM AUTHOR]