Lüleburgaz (, Modern Greek: Λουλέ Μπουργκάς Lule Burgas, Bulgarian: Люлебургаз Lyuleburgaz), Bergoulion (Ancient Greek: Βεργούλιον) or Arcadiopolis (Ancient Greek: Αρκαδιόυπολις Arkadiópolis) is the largest city and district of Kırklareli Province in the Marmara region of Turkey. Located near the border with Bulgaria within the historic region of East Thrace in Rumelia, the city is home to many Balkan Turks from Albania, Bulgaria, Greece, Romania and ex-Yugoslavia who immigrated to Turkey since the 19th century. Lüleburgaz is a hub for road and rail transportation, with the city being connected to Istanbul and Edirne by the Istanbul-Kapikule Regional Train and to Plovdiv, Sofia, Belgrade, Bucharest and Budapest by the Bosphorus Express and the Istanbul-Sofia Express. The city has an urban population of 122,635 (2021 census). Its best known attraction is the 16th-century Sokollu Mehmed Pasha Mosque, named after the Grand Vizier Mehmet Paşa Sokolović and designed by the Ottoman chief architect Mimar Sinan who also designed a bridge for the city. History The city used to be the capital of the Roman province of Europa, established by the Roman Emperor Diocletian in 294. The city's ancient name was Bergula but Emperor Theodosius I changed it to Arcadiopolis in honour of his son and successor Arcadius. The city of Arcadiopolis fell to Attila the Hun during his campaign against the Eastern Roman Empire in 443 AD. During the revolt of Thomas the Slav against Michael II, the city was Thomas' last refuge after the defection of his troops in 823. Michael II invested the city and after more than five months of siege, the exhausted and starving troops gave up their leader in exchange for an imperial pardon. Thomas was handed over on a donkey and tortured. The Battle of Arcadiopolis of 970 saw the Byzantine forces defeat an invading Kievan-Pecheneg-Magyar force who were aiming to capture Constantinople, to the east. As the capital of the Roman province of Europa, Acradiopolis had its own bishop, who was recorded as attending a number of important church councils; it was noted as an autocephalous archbishopric by the seventh century. It is no longer a residential bishopric, although the Diocese of Arcadiopolis survives as a Roman Catholic titular see. Marcel Lefebvre, the founder of the Society of Saint Pius X, was one of its titular bishops. The Battle of Lüleburgas was fought between 28 October and 2 November 1912 during the First Balkan War. The city