Berat Castle, also known as Kalaja, is a historic fortress located in the city of Berat, Albania. The castle is situated on a hill overlooking the city and is surrounded by high walls that date back to the 4th century BC. The castle has been occupied by various empires throughout history, including the Illyrians, Romans, Byzantines, Ottomans, and Albanians.

The castle consists of several buildings and structures, including churches, mosques, and a museum. One of the most notable structures within the castle is the Red Mosque, also known as the Mosque of Mehmed Bey, which was built in the 15th century. Another notable structure is the Church of Saint Mary of Blachernae, which dates back to the 13th century.

Berat Castle was designated as a UNESCO World Heritage Site in 2008, along with the city of Berat as a whole. The castle is an important cultural and historical landmark in Albania and attracts visitors from all over the world who come to explore its rich history and admire its stunning architecture.