The koule of Kalonyktis is located on the hill of Agiasmatsi on the outskirts of the village of Kalonyktis in the province of Rethymno. This large tower was built by the Ottomans after the Great Cretan Revolution of 1866, being part of the large network of towers - koules - for the control of the Cretan revolutionaries.
The area of Koules was probably a theater of conflict during the battle of Kalonyktis on December 9, 1868. At that time, a group of Cretans led by Petropoulakis were forced to retreat to Roustka by the Turkish forces, counting three dead fighters. The battle of Agiasmatsi took place on the same hill in 1878 and was victorious in favor of the Cretan revolutionaries.
The masonry of the tower is preserved at a relatively high height, compared to most leveled towers of the same period.