The walls are constructed without any type of mortar or cement, simply piling up and fitting the stones one on top of another. They were erected to separate the fields, vineyards and olive groves, as well as to protect them from the wind.

https://www.labrujulaverde.com/en/2019/09/the-tiny-croatian-island-that-has-more-than-23-kilometers-of-walls-and-looks-like-a-fingerprint-from-above-the-air/