The Lakatnik (Osikovo) Rocks are a set of beautiful escarpments, slopes, pyramids, pillars, caves and karst springs located on the left bank of the Iskar River between the rivers Opletnenska and Proboinitsa. The name of the rocks, and of the well-known train station lying below them, comes from the sharp bend of the Iskar River right there resembling an elbow (lakat in Bulgarian).
Lakatnik rocks are mainly sediments of limestone from different geological eras and sandstones, with deposits hailing from different eras clearly distinguished. The formation of the rock set is related to the drainage of the Sofia Pliocene basin north through the Old Mountain and the Iskar Gorge formation while the ancient sea was receding. The deep erosion process has repeatedly subsided, which has contributed to the development of a multi-layered karst system. The Lakatnik rocks were declared a natural landmark in 1989 and fall within the subsequently established Vratsa Mountain Nature Park.
The most attractive part of the escarpment at the Temnata Dupka (Dark Hole) and the Zhytolyub karst spring is visited by tourists throughout the year. These cliffs saw the 1925 inception of Bulgarian alpinism, when an Alpine rope was used for the first time nationwide. If you come by car or train from Sofia you will see a small red cottage perched on the rocks. This is the Eagle's Nest shelter, built in 1938 by climbers from the Bulgarian Alpine Club, the forerunner of the Bulgarian Climbing and Mountaineering Federation.
The beauty of Iskar Gorge, its proximity to Sofia, as well as the Multiple tourist trails and caves attract tourists at any time of the year. The region is one of the most popular mountaineering places in Bulgaria - there are more than 20 alpine trails with different degrees of toughness.
There are also over 100 caves in the area, most of which are hard-to-reach karst formations - you will often find cavers in the area. Legends about hidden treasures have also been bandied about, which makes the place a favourite for treasure hunters as well.