Rising on Tsarevets hill was the citadel (the fortified central part) of the medieval town. This main fortress of the medieval capital protected the Palace of the Bulgarian Kings – an architectural compound, strongly fortified by fortress walls and towers, covering an area of 4,772 sq m.
The representative and administrative buildings, connected with the functioning of the authorities and the royal premises were to be found in this independent fortress. The palace Church of St Paraskeva (St Petka) was also located here, buried in which were members of the ruling dynasty. The Residence of the Bulgarian Patriarchs (Patriarchate) rose on the highest place of the hill. It included an architectural compound of buildings, made up as an independent fortress in an irregular angular shape (with fortress walls, gates and towers) spreading on a total area of about 3,000 sq m. The patriarchy church of the Holy Ascension was in the center of the inner courtyard. This is a cross-domed, three apse church with two narthexes. There is a premise attached to the south facade of the church, which had been a belfry tower – a rare phenomenon in Balkan church architecture.
The uncovered numerous fragments of multicoloured marble and glazed ceramic slabs are evidence of the elaborate decoration of the church. The floor mosaic had been particularly beautiful. Kept in the church were the relics of St Mihail Voin [Warrior], a Bulgarian boyar, honoured as a warrior and a healer. They had been brought by Tsar Karloyan in the early 13th century. Two compounds are also situated in the citadel, inhabited by members of the aristocracy. The remaining area was densely built with two-storeyed dwellings, divided in residential districts. The foundations of more than 320 residential and housing buildings have been unearthed.
Every residential district had a church of its own. Perilously overhanging the Yantra River in the southeast end of Tsarevets is the Lobnata Skala [Execution Rock], from which condemned traitors were thrown into the river. A tower, protecting the Frankhissar Gate and the water reservoir of the Yantra, rose in the southeast end of Tsarevets. Legend associates this tower with Emperor Baldwin, taken prisoner by Tsar Kaloyan in the battle at Adrianople in 1205. The tower, commonly known as Baldwin’s Tower, was restored after a design by Architect Rashenov in 1930-1932.