Sidirokastro (; Bulgarian and Macedonian: Valovišta; ) is a town and a former municipality in the Serres regional unit, Greece. Since the 2011 local government reform it is part of the municipality Sintiki, of which it is the seat and a municipal unit. It is built near the fertile valley of the river Strymonas, on the bank of the Krousovitis River. Sidirokastro is situated on the European route E79 and the main road from northern Greece (Thessaloniki) to Bulgaria. It has a number of tourist sights, such as the medieval stone castle, Byzantine ruins, and natural spas. General information Sidirokastro is located 25 km to the northwest of the town of Serres, between the Vrontous and Angistro mountains (to the north) and the river Strymonas (to the west). The 2011 census recorded 9,294 residents in the municipal unit of Sidirokastro, while there were 5,693 residents recorded in the community of Sidirokastro and 5,177 in the settlement. The municipal unit has an area of 196.554 km2. The town is crossed by the Krousovitis River, one of the Strymonas' tributaries, which divides the town into two sections. These sections are connected by two bridges: Stavrou and Kalkani. The landscape is made even prettier thanks to the Maimouda rivulet and its miniature bridges. Sidirokastro's population is a blend of indigenous people and descendants of the early 20th century waves of refugees from Asia Minor (people who sought asylum in Greece from the wars and conflicts of that period). Sidirokastro took in refugees from Melnik in 1913; from East Thrace (European Turkey) after the 1922 onslaught that followed the Greco-Turkish Wars in Asia Minor; from Pontus, Vlachs and people from all over Greece. History Sidirokastro's history reaches a long way back in time. There are Palaeolithic ruins here, and references to the area are found in Homer and Herodotus. Its ancient inhabitants migrated to Sidirokastro from the island of Limnos. The area's first inhabitants were of the Sintian tribe, after which Sintiki Province is named. According to the statistics of Geographers Dimitri Mishev and D.M. Brancoff, the town had a total Christian population of 1.535 people in 1905, consisting of 864 Bulgarian Patriarchist Grecomans, 245 Greek Christians, 240 Vlachs, 162 Roma people and 24 Exarchist Bulgarians. On September 20, 1383, Sidirokastro was overtaken by Ottoman forces and remained under their rule for 529 years. Its name was changed to "Demir Hisar" (Also called "Timurhisar").