Middle Ages, similarly reported in On Genesis that "on the peak of Mount Olympus, which is said to rise above the area of this humid air, we are told, certain letters are regularly made in the dust and are a year later found whole and unmarred by those who climb that mountain for their solemn memorials." The third highest peak of Mt Olympus, called Agios Antonios (Άγιος Αντώνιος "Saint Anthony", , 2,817 m), is known to have been the site of a sanctuary of Zeus in antiquity based on archaeological finds discovered in 1961. In the modern era, a series of explorers tried to study the mountain and to reach its summit. Examples include the French archaeologist Leon Heuzey (1855), the German explorer Heinrich Barth (1862), and the German engineer Edward Richter. Richter tried to reach the summit in 1911 but was abducted by klephts, who also killed the Ottoman gendarmes that accompanied him. It was just one year after the liberation of northern Greece from Ottoman rule, on 2 August 1913, that the summit of Olympus was finally reached. The Swiss Frédéric Boissonnas and Daniel Baud-Bovy, aided by a hunter of wild goats from Litochoro, Christos Kakkalos, were the first to reach Greece's highest peak. Kakkalos, who had much experience climbing Olympus, was the first of the three to climb Mytikas. Afterwards, and until his death in 1976, he was the official guide on Olympus. In 1921, he and Marcel Kurz reached the second highest summit of Olympus, Stefani. Based on these explorations, Kurz in 1923 edited Le Mont Olympe, a book that includes the first detailed map of the summits. In 1928, the painter Vasilis Ithakisios climbed Olympus together with Kakkalos, reaching a cave that he named Shelter of the Muses, and he spent many summers painting views of the mountain. Olympus was later photographed and mapped in detail by others, and a series of successful climbs and winter ascents of the steepest summits in difficult weather conditions took place. Climbing Mount Olympus is a non-technical hike, except for the final section from the Skala summit to the Mytikas peak, which is a YDS class 3 rock scramble. It is estimated that 10,000 people climb Mount Olympus each year, most of them reaching only the Skolio summit. Most climbs of Mount Olympus start from the town of Litochoro, which took the name City of Gods because of its