Pyramidal form made of rustically processed stone in the Pioneers` park in Belgrade, based on its widely spread belief, represents the replica of the observation post of the Serbian Army from Kajmakčalan, from the Salonika front that is, the observation post of the High Command of the Serbian Army from the Salonika front, which was located on Jelak, on the Moglen mountain, from where the regent Aleksandar Karađorđević and the commander in chief Živojin Mišić and the members of his headquarters watched the battle on the day of the breakthrough of the Salonika front, on 15 September 1918. Allegedly, the observation post was moved to Belgrade in 1928. There are other records too, which identify this structure as the imitation of the Grotto cave, built during the reign of King Milan Obrenović, which served in a decorative purpose. The third sources state that the construction was built as a belvedere, after the First World War, during the reign of King Aleksandar. The data about the existence of the observation post from the Salonika front [3] in the Pioneers` park in Belgrade appears in the daily paper Politika, from 5 November 1983. In the above-mentioned text, the author dr Milorad Tešić mentions the states which are mostly used even nowadays. In his letter to the Republic Cultural Heritage Protection Institute, professor Tešić mentioned as the source that during 1935 he was listening to the lectures „The History of Wars, where colonel Jeremija Stanojević said that „the observation post of the High Command of Serbian Army on Jelak was soon after the First World war moved to Belgrade and that later on, during his military service, as an officer in the Guard from 1936 to 1941 he heard that information from the senior officers. Before the mentioned text by dr Milorad Tešić, there was an oral story that the mentioned structure was the park structure from Romanticism, and in 1980 it was described as the park decoration. (text written by the architect V. Đorđević in the magazine Architecture-Urbanism, no. 59, from 1980). Trying to clarify the origin of this object, and in order to find the documented material related to the observation post, The Cultural Heritage Protection Institute of the City of Belgrade conducted extensive researches during 1988/1989.