This national nature reserve is a land of high rocky cliffs and riverside marshes, 4 km in length below the former mill of the settlement of Karba. It has an area of 59 ha and an elevation of 247 - 303 m above sea level. Declared a protected region in 1967, it has nonetheless been a popular hiking destination ever since the 19th century. In the early 20th century, the owner of the manorial estate, Count Vincenc Karel Kounic, arranged the surroundings of the Zahrádky chateau into a romantic landscape ensemble, including Peklo. The Robči brook was made navigable along its entire length in the protected area, and boating along it was one of the aristocratic owners’ favourite sports.
During the Thirty Years’ War, the Austro-Prussian War and World War Two, Peklo served as a hiding place from attacking armies for the inhabitants of nearby villages. In 1881, Peklo was seriously threatened by plans to build a railway line through it. Under pressure from the naturalists’ association, the ‘Excursions-Club’, as well as the general public and the land’s owner, Count Kinský, the project was re-considered, and in 1898 a viaduct was built spanning the valley near Karba. The track was opened for rail travel on December 29, 1898. The steel rail bridge with its rounded arches, 209 m long and 24 m high, has been nominated for protection as a technical landmark. At present, the Peklo Valley contains a 4 km-long marked nature trail, restricted to hikers on foot.