EN
April 2015, a preventive archaeological and architectural inyestigation, preceding the planned renoyation and installation of an under-floor heating system, was carried out in St Giless church in Cracow. The scope of the inyestigation included smallscale test holes in the churchs floor, and was subject to the Schedule of the heating system installation. Despite these constraints, the inyestigation has brought new information on the appearance of the church in its Gothic phase. Among the most important findings was the discoyery of remnants of a central pier of the Gothic nave whose presence has hitherto been a matter of conjecture. This finding assigns the fourteenth-century church of St Giles to a numerous group of two-aisled Cracow Gothic churches, nowadays usually rebuilt or no longer surviving, whose construction has been conyentionally associated with the royal building lodge of King Casimir the Great. It has been established that the pier had an octagonal plan and its placement with regard to the walls of the nave and the location of the buttresses conditioned a particular construction of the yaulting. No remnants immediately related to the alleged earlier, Romanesąue church, whose existence is known from primary sources, have been found. It has been established, however, that in the period before the construction of the Gothic church, a cobblestone surface, located about 90 cm below the present floor level, had existed within the present nave and had been used for an extensive period. It was from this level that the pier of the fourteenth-century church was raised. It has been also recorded that the occupation level of the Gothic church was barely a dozen centimetres lower than the present floor level, created at the beginning of the twentieth century. The remaining findings revealed fragmentary information on the foundations of the Gothic nave and on the transformations of the church in the early modern period, thus supplementing the current State of research and making it possible to specify objectives for future research.