The excavation carried out by István Schönvisner, under what is today Florian Square (Budapest, Distr. III.), next to the Villa Torcularia, during which he revealed the sudatorium of Aquincum’s bigger bath, the Thermae Maiores began on 10th February 1778. Thanks to this excavation and the rapid publication of the results, the professor of antiquity and numismatics of Buda University became the founder of provincial archaeological research in Pannonia. In the same year he published the results of the exploration in De Ruderibus Laconici Caldariique Romani..., which – like Schönvisner’s other works – is revolutionary. He systematically processed the inscribed and figurative fragments which were discovered during the excavation and gave a complete overview of the era’s cultural history. In this paper, I would like to demonstrate the historical and cultural historical importance of this work, present its structure, the topics discussed, and the results by which István Schönvisner laid down the foundations of scientific classical archaeology in Hungary.