The highest of Plovdiv’s syenite hills has had many names over the centuries. Mostly known as the Youth Hill, it has before been known as Dzhendem Tepe, Djinn Tepe, and in Thracian times – the Hill of the Dryad Nymphs. It is believed that there used to be a settlement or sanctuary during the days of the Thracians, with a colossal bronze statue of the god Apollo standing atop the hill. In a later historical period, a large early-Christian basilica was built on the site of the pagan statue. The Youth Hill is the first to be declared a protected area due to the presence of endangered plant life that is normally unusual for this type of environment. The rare plants Hypericum setiferum, Genista rumelica, Chamaecytisus frivaldszkyanus, Astragalus physocalix and Achiliea thracica grow on the southern side of the hill.