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 the year. Mists are common in the cooler months, especially along the banks of the Maritsa. On average there are 33 days with mist during the year. The history of Plovdiv spans more than eight millennia. Numerous nations have left their traces on the cultural layers of the city. The earliest signs of habitation on the territory of Plovdiv date as far back as the 6th millennium BCE. Plovdiv has settlement traces including necropolises dating from the Neolithic era, roughly 6000–5000 BCE, like the mounds Yasa Tepe 1 in Philipovo district and Yasa Tepe 2 in Lauta park. Archaeologists have