The Municipality of Plovdiv is situated in the lowland altitude zone (from 0 to 200 m above sea level) and in the morphostructure of the Balkans. In the lowland morphostructure are formed six valley hills - these are the Plovdiv hills. They are unique geomorphological formations, which are major environment forming factors and symbols of the city - "Youth Hill" (Dzhendem Tepe) - 285.5 m above sea level, "Hill of the Liberators" (Bunardzhika) - 265 m above sea level, "Danov Hill" (Sahat Tepe) - 227 m above sea level, the Three Hills (Trimontium), consisting of Taksim Tepe - 195 m above sea level, Dzhambaz Tepe - 212 m above sea level and Nebet Tepe - 207 m above sea level. Of these, "Youth Hill", "Danov Hill" and "Hill of the Liberators" have been declared natural landmarks. The hills are located in urban environment and are part of the tourist routes of the city. They are accessible for observation via roads. Until the 20th century, there were seven hills, but in the 1930s "Markovo Tepe" was partially destroyed due to the minning of rock material for paving stones.