The administrative building is situated on the most eastern low terrace whose  supporting wall separates it on the west from the Patriarch’s complex. The building is constructed as a pagan proto- Bulgarian chapel probably in the beginning of the 9th century. It consists of two entered quadrangles with outer sizes 18 X 14  m. As a result unsegmented corridors have been formed around the inner quadrangle  from three sides. The northern corridor is wider than the southern.

After Bulgaria’s Christianization it was not ruined like many shrines but reconstructed and used as a representative secular building. The southern corridor is formed as three section entrance. During the capital period its inner space was renewed which is evident by the parts of decoration and transparent glass found. The fragments of bases, columns and capitals found prove the existence of colonnades. In view of the proximity to the Eastern gate of the Inner town as well it is possible that this was namely the place where guests were welcomed for the first time while waiting to meet the ruler. Like the Palaces the spaces around the building here are formed through pavements covering the pavement ways of three water pipes and two canals.

During the Byzantium rule the region around the building is densely built up in accordance with the needs of the Byzantine administration. The pavements around the building are preserved. It is possible that some of the water pipes and canals continued to be used. A two section building was adjoining on the east directed to east- west. The pavement preserved on the north leading to the Building with furnaces show that probably there used to be an entrance on the north during that period. The building becomes a strategy for the town’s Byzantine administration. The biggest collection of Byzantine lead seals was found here in situ /on site/- more than 500 pieces, covering the period from Preslav’s falling in 971 to 1088. Lead kernels and moulds for their casting were also found. That is why the building was named Administrative.