The article presents researches and analyzes of cross-reinforced hollow-block ceilings with structure similar to the „Westphalian Ceilings”, in a building from 1915. The tested building was built at a time when slab and reinforced concrete theories were not yet developed for cross-reinforcement systems, and the reinforcement for them was determined on the basis of test loads. The structure and actual technical condition of the ceilings after over 100 years of use were discussed. The results of their analysis are presented with 2 calculation models: in the form of a monolithic reinforced concrete grate and a rectangular slab, taking into account the cooperation of the compressed upper shelves of ceramic blocks. The reinforcement cross-sections obtained from the calculations were compared with the reinforcement used in the existing ceiling structures and conclusions regarding their load- -bearing capacity were presented.