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 was inaugurated in the city. In the beginning of the 20th century, Plovdiv grew as a significant industrial and commercial center with well-developed light and food industry. In 1927 the electrification of Plovdiv has started. German, French, and Belgian capital was invested in the city in development of modern trade, banking, and industry. In 1939 there were 16,000 craftsmen and 17,000 workers in manufacturing factories, mainly for food and tobacco processing. During the Second World War, the tobacco industry expanded as well as the export of fruit and vegetables. In 1943, 1,500 Jews were saved from deportation in concentration camps