Mysionis was a large ancient town and fortress. It is located 7 km away of town of Targovishte in region Krumovo Kale, on the northern edge of the steep gorge of the river Vrana in Preslav Mountains.
The site dates back to 6th-7th centuries. After excavations there were found remains of fortress walls 3-4 meters in height, remains of a large church, guard and residential buildings. The slopes of the hills were occupied of neighborhoods and in one of them was found a second large Christian church.
In the vicinity were found also marble columns, antique stone objects, Roman pottery, medieval cemeteries and others. Probably Mysionis existed until the end of the 14th century and was destroyed during the Ottoman invasion.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.