In this paper we present 30 preserved boundary marks of the cadastral municipalities from the period of the Franciscan cadastral survey from 1818 to 1819, which we found in the vicinity of villages of Sežana, Lokev, Rodik, Markovščina and Materija in Slovenia. The studied boundary marks of the cadastral municipalities are 70 cm or more high, mostly with carved inscriptions, sometimes also with coats of arms, or have a form of isolated, larger rocks, which also have carved inscriptions. These boundary marks still mark the official boundaries of the cadastral municipalities today. But some of them also played a more important role in the past, as they marked the boundaries of the districts. Some once had a simultaneous cadastral and trigonometric role, and some still retain this dual role today. Quite a few of these boundary marks are linked to the preserved local oral tradition, associated with the Schwarzenegg estate of the Counts of Petazzi and various mythical monsters that guard the boundaries of the cadastral municipalities. With the help of two of them, Križen drev and Kokoš (Jermanec), we have discovered and proved, how the borders of the cadastral municipalities in this area date back at least to the 16th century. Therefore, we can consider the present-day boundaries of the cadastral municipalities in this area of Slovenia as one of the longest-lasting and preserved spatial division.