This division of ownership caused disputes between Sezima's brother Zdeněk and Archbishop Arnošt of Pardubice.

Among the most important members of this family was Joanna of Rožmitál, the Czech queen and wife of King George of Poděbrady.

Her brother Jaroslav Lev of Rožmitál led the diplomatic mission of George of Poděbrady, whose task was to unite the European monarchical courts against the Turks.

During the time of Zdeněk Lev, the castle underwent significant structural modifications, which served as the basis for the later Renaissance reconstruction.

Zdeněk Lev of Rožmitál led an expensive life and also lent considerable sums to nobles and the king.

[2] In 1550–1555, the Rožmitál estate was gradually bought from its creditors by Florián Gryspek of Gryspach, a nobleman of Bavarian-Austrian origin.

Gryspek established a brewery, a bakery, granaries and had water brought in from a nearby hill through wooden pipes.

In 1974 the castle was transferred to the property of town of Rožmitál, which moved the inhabitants of the apartments to a newly built housing estate.

[10] In the mid-1990s, the town of Rožmitál repaired parts of the castle with financial support from the Ministry of Culture, but the question of its use was still unclear.

The castle was transferred to a private company, Trinity Coop, of which Roderick Marshall became the majority owner and the Archbishopric of Prague retained a minority share.

Due to the lack of regular maintenance, the castle became a target for vandals and the adjacent grounds were overgrown with trees.

With its patronage, the Rožmitálský zámek association was formed in 2019, with the aim of making the castle accessible to the public and engaging it in community life.

Since 2019, the castle has been managed by the voluntary association Rožmitálský zámek, which opens the castle to the public during the summer season and organises various cultural events – concerts, theatrical shows, workshops, working holidays,[17] art exhibitions[18] or summer cinema in the courtyard.

From the earliest construction phase, a perimeter wall has been preserved in the masonry of the castle, which defined an approximately oval area.

According to historical descriptions and depictions, the castle was fortified with ramparts and a wall with round bastions or towers during the late Gothic period.