About one kilometer from the picturesque town of Melnik, you can find the remains of the medieval Fortress of Despot Alexius Slav, nephew of Tsar Kaloyan. According to historians, it was built in the 11th century, with an expansion and improvement taking place in the 13th century. This was the period when it was under the control of Alexius Slav, which is why it is named after him. The fortress covers an area of 3,000 square meters. Today, parts of the walls still remain, and in some places rise to over 10 meters.