The village of Mrač was first mentioned in 1318 in connection with records concerning a local nobleman Zdislav of Mrač. His seat was probably located in an older fortress from which only a fortification located maybe only 100 metres from the currently preserved newer fortress remained. The fortress was located on a low hill with a round top which used to have a log building on its top. There are records concerning noblemen brothers from Mrač: Oldřich, Vilém, and Ješata from 1356.