Near Simeonovgrad lie the ruins of the Ancient Roman and Byzantine fortress of Constantia (Greek: Κωνσταντία) from the Late Antiquity (4th century AD), which developed into one of the large towns of Northern Thrace until the beginning of the 13th century.
The town's historical names were Seymen and later, during 1872–1929, Tarnovo–Seymen (Bulgarian: Търново-Сеймен) – named after the Ottoman-era seymen paramilitary units. For most of the Socialist period, between 1946–1981, the town was named Maritza (Bulgarian: Марица), after the river. The present name Simeonovgrad literally means "town of Simeon", a reference to the 10th-century Bulgarian king.
Municipality
Simeonovgrad is also the seat of Simeonovgrad municipality (part of Haskovo Province), which includes the following 8 villages:
