The oldest and most important building is the so-called Little Castle with a castle tower (see Castle No. 59 - Little Castle, Castle No. 59 - Castle Tower). In the left-hand corner of the courtyard there is a staircase leading to this building which was mentioned as early as the first half of the 13th century as a mighty cylindrical tower with a palace. At the time of the rule of Vilém von Rosenberg around the year 1580, the comprehenxsive re-building of the early Gothic Little Castle was carried out by architect Baldassare Maggi d'Arogno and the austere Gothic palace was converted into the residential house built in Renaissance style. The tower was remodelled and the arcade gallery was established on the top. In 1591, the painter Bartoloměj Beránek - Jelínek decorated the castle tower with paintings using figural and architectural motifs. After the document case was opened on August 22, 1991 the dates of building stages in 1690, 1794 and 1947 were made accurate thanks to the discovered documents. Current restoration and reconstruction activities aspire to rehabilitate the Renaissance architectonic features of the tower and Little Castle that are partly visible or covered with plaster from the 19th century.
Source: http://www.zamek-ceskykrumlov.eu/description-of-objects-within-the-castle/