The article attempts to resolve the question concerning the number of castles in present-day Poland as well as the possibility of providing legal protection to existing resources in the contemporary economic and legal conditions, with particular stress on the ownership aspects. The authoress analysed factors causing the absence of an unambiguous answer relating to the size of the resource, with attention focused on questions associated with terminology applied for a precise definition of the affiliation of particular monuments to the 'castles in Poland' category as well as its practical application for listing the castles in the register of historical monuments. The article discusses the following concepts: historical ruins and the ruins of a monument, permanent ruins of a castle and its remnants, fragments and relics, and 'the ruins of a castle on which a part of the castle or the whole castle had been built' (this concept is as yet without a shorter counterpart).