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 Airport and a tie-up between Hainan and Plovdiv Airport Invest. On 28 March 2018, Bulgarian Government awarded the consortium of HNA Group and Plovdiv Airport Invest a 35-year-long concession on Plovdiv airport in return for investments reaching €79 million, including a new cargo and passenger terminal. On 19 of July the consortium of HNA Group and Plovdiv Airport Invest have declared that it won't sign the concession contract which opens the road for the classified on the second place to take the concession. On the west side of the airport is located 24th Helicopter Air Base of the Bulgarian Air Force,