Plovdiv city was possibly at times a vassal of Bulgaria or Venice. Ivan Asen II conquered the duchy finally in 1230 but the city had possibly been conquered earlier. Afterwards, Plovdiv was conquered by Byzantium. According to some information, by 1300 Plovdiv was a possession of Theodore Svetoslav of Bulgaria. It was conquered from Byzantium by George Terter II of Bulgaria in 1322. Andronikos III Palaiologos unsuccessfully besieged the city, but a treaty restored Byzantine rule once again in 1323. In 1344 the city and eight other cities were surrendered to Bulgaria by the regency for John V Palaiologos as the
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.