One of the forts, Fort Lisse, was built on a hill which rises from the Nevrokopi Plane, as is east of Ochyro Village.
Its fortifications consist of four groups of bunkers (Chelones) across the hill, with underground tunnels that totalling more than 950m. Two of the underground tunnel complexes are connected by passages, while the other two are independent defensive installations.
The fort has machine gun posts, living and storage areas, water tanks, generators, weaponry and space for military vehicles. It was staffed by 12 officers and 457 soldiers.
Due to the high level of secrecy and the need for camouflage, the fort installations are not easy to see from the outside and many of the entry points are difficult. Only one Cheloni is available to visit.