Acoustical reconstruction of ancient spaces, existing in very different conditions or not existing anymore, is becoming an increasingly popular activity in different research fields. Availability of several softwares brought acoustic simulation out of specialized labs and made it possible for a much broader audience to take advantage of their potentials. However, like any other simulation tool, reliability of the results needs to be carefully pondered as it depends on a number of fac-tors pertaining to proper knowledge of the simulation process and of the characteristics of the building to be simulated.