Extensive and deep cellars are still preserved under the buildings forming the Old Post Office. However, only 2 of them are still accessible to the public. Their arches are made of brick and stone. A third cellar can be seen through a floor cavity from the vantage point of the staircase in the main building’s cellar. An earthen mound in the forefront of the room naturally evokes a blind faith in the legends depicting secret passage leading from here to as far away as the Church of the Holy Virgin Ascention basement in Pozořice.

From the cellar located under the room in which there is a stylish restaurant today, you can return to ground level by climbing 28 stairs. Another very often repeated legend tells that after the Battle at Slavkov, the victorious French waded in ankle-deep wine, in this very same deep cellar.