The Avanta-River Castle was built on a hill 100 meters from the last house of the village of Avanta and approximately 10 km away from the city of Alexandroupoli. The specific date of construction is unclear, but according to the prevailing opinion of researchers, the castle was built approximately nearly the 13th century.
The castle was constructed during the medieval era and has three square towers which regardless of the years are still preserved quite well. Additionally, some parts of the double protecting wall are still standing.
The role of the structure was to protect the local population from the raids of Bulgarians and those of other northern tribes. While another crucial role was to guard and control the passage of the Komotini plain to the east.