From time immemorial boulders have played an important function in social life. They had astronomical, religious, juridical, memorial and ceremonial meanings. First when the boulders were recognised as aesthetic and geological features they were pointed out as monuments. In The Netherlands roughly tree types of geological boul -der monuments canbe distinguished according to their origin: southern fluvial erratics, northern glacial erratics and in situ cemented boulders. Several examples of geological monuments and reservations are mentioned. Many boulders have been replaced. According to the author 's opinion boulders should in principle remain on their original location. Exceptions can be made for boulders that have to be moved because of necessary works. Nevertheless these boulders should be placed ona marked spot nearby the original location.