Plovdiv of which are high. Because of these hills, Plovdiv is often referred to in Bulgaria as "The City of the Seven Hills". Plovdiv is host to a huge variety of cultural events such as the International Fair Plovdiv, the international theatrical festival "A stage on a crossroad", the TV festival "The golden chest", and many more novel festivals, such as Night/Plovdiv in September, Kapana Fest, and Opera Open. There are many preserved ruins such as the ancient Plovdiv Roman theatre, a Roman odeon, a Roman aqueduct, the Plovdiv Roman Stadium, the archaeological complex Eirene, and others. The oldest American educational
Plovdiv is the second or the third-largest cosmopolitan city inhabited by Bulgarians, after Sofia and possibly Varna. According to the 2001 census, out of a population of 338,224 inhabitants, the Bulgarians numbered 302,858 (90%). Stolipinovo in Plovdiv is the largest Roma neighbourhood in the Balkans, having a population of around 20,000 alone; further Roma ghettos are Hadji Hassan Mahala and Sheker Mahala. Therefore, the census number is a deflation of the number of Roma people, and they are most likely the second-largest group after the Bulgarians, most of all because the Muslim Roma in Plovdiv claim to be of Turkish ethnicity