Tuida is a Late Antique and Medieval fortress. It is located on the Hisarlaka hill in the northeastern part of Sliven, right next to the Novo Selo neighbourhood. In the past, the area was inhabited by Thracian tribes, ancient Romans and medieval Bulgarians. From the site of the fortress there is a unique view of the majestic Blue Stones and the town of Sliven. Tens of thousands of Bulgarian and foreign tourists visit the site every year, regardless of the season. The greatest interest is in the museum animation, which is offered daily in the site – archery, demonstrations of traditional military arts, life style and culture from the period of the First Bulgarian Kingdom.