Plovdiv city was originally a Thracian settlement and subsequently was invaded by Persians, Greeks, Celts, Romans, Goths, Huns, Bulgars, Slavs, Rus people, Crusaders, and Turks. On 4 January 1878, Plovdiv was liberated from Ottoman rule by the Russian army. It remained within the borders of Bulgaria until July of the same year, when it became the capital of the autonomous Ottoman region of Eastern Rumelia. In 1885, Plovdiv and Eastern Rumelia joined Bulgaria. Plovdiv is situated in a fertile region of south-central Bulgaria on the two banks of the Maritsa River. The city has historically developed on seven syenite hills, some
Plovdiv Arts; and others. The 2009 International Olympiad in Informatics (IOI) was held at the University of Plovdiv "Paisiy Hilendarski", between 8 and 15 August 2009. The 2009 IOI Honorary Patron was Bulgarian President Georgi Parvanov. Between 1875 and 1906, the Zariphios School was one of the local Greek educational institutions that provided elementary and secondary education. Plovdiv Sports Complex consists of Plovdiv Stadium with several additional football fields, tennis courts, swimming pools, a rowing base with a 2 km-long channel, restaurants, and cafés in a spacious park in the western part of the city just south of the Maritsa river.