Sérres (Greek: Σέρρες) is a city in Macedonia, Greece, capital of the Serres regional unit and second largest city in the region of Central Macedonia, after Thessaloniki. Serres is one of the administrative and economic centers of Northern Greece. The city is situated in a fertile plain at an elevation of about 70 metres (230 feet), some 24 kilometres (15 miles) northeast of the Strymon river and 69 km (43 mi) north-east of Thessaloniki, respectively. Serres’ official municipal population was 76,817 in 2011 with the total number of people living in the city and its immediate surroundings estimated at around 100,000. The city is home to the Department of Physical Education and Sport Science of the Aristotle University of Thessaloniki (Greek: Τ.Ε.Φ.Α.Α. Σερρών) and the Technological Educational Institute of Central Macedonia (Greek: ΤΕΙ Κεντρικής Μακεδονίας), composed of the School of Technological Applications, the School of Management and Finance and the School of Graphic Arts and Design, with at least 10,000 Greek and international students.
The Ancient Greek historian Herodotus mentions the city as Siris (Σίρις) in the 5th century BC. Theopompus refers to the city as Sirra (Σίρρα). Later, it is mentioned as Sirae, in the plural, by the Roman historian Livy. Since then the name of the city has remained plural and by the 5th century AD it was already in the contemporary form as Serrae or Sérrai(Σέρραι), which remained the Katharevousa form for the name till modern times. In the local Greek dialect, the city is known as “ta Serras” (τα Σέρρας), which is actually a corruption of the plural Accusative “tas Serras” (τάς Σέρρας) of the archaic form “ai Serrai” (αι Σέρραι). Τhe oldest mention of this form is attested in a document of the Docheiariou Monastery in Mount Athos from 1383, while there are many other such references in documents from the 16th, 17th, 18th and 19th centuries. It was known as Serez or Siroz in Turkish. In the Slavic languages, the city is known as Ser in Serbian, while in Bulgarian it is known as Syar (Сяр) or Ser.
Although the earliest mention of Serres (as Siris) is dating in the 5th century BC (Herodotus), the city was founded long before the Trojan War, probably at the beginning of the 2nd millennium BC. The ancient city was built on a high and steep hill (known as “Koulas”) just north of Serres. It held a very strategic position, since it controlled a land road, which following the valley of the river Strymon led from the shores of Strymonian Gulf to the Danubian countries.
The most ancient known inhabitants of the area were the Bryges (Phrygians) and Strymonians; afterwards (since 1100 BC) were Siriopaiones  and finally (from the early 5th century BC until the end of antiquity) the Thracian tribe of Odomantes. These populations mainly engaged in agriculture and cattle-raising especially worshiped the Sun, the deified river Strymon and later the “Thracian horseman“.