The remains of Kaleto stronghold known also as Kavursko kale are located some 4 km west of the town of Devin. The stronghold was erected on a steep rocky hill, naturally protected in all three directions. The place offers magnificent view to the region and the river below. It is believed that the stronghold was built around 6th and 10th century. It is made of stone soldered with white mortar. Its walls were 1.5 m thick. Nowadays, only the eastern wall with a length of 50 m and a height of 50-70 cm is partially preserved. The remains of several square rooms or towers could also be seen. In the center of the stronghold there is a spring, which most probably is one of the reasons the facility was built here.
Artifacts of spears and iron arrows were also found around the site.
Kavursko kale is one of the last fortifications in the Rhodopes surrendering to the invading ottomans, where its siege lasted 3 months. The access to Kaleto is via a marked trail starting from the main ecotrail along Devinska river.