- Sérres (Greek: Σέρρες, katharevousa: Σέρραι, Sérrai) 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 theTechnological 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.