The courtyard, surrounded by its colonnade, is the result of the construction of a new royal residence started by Alexander the Jagiellonian and completed around 1540. The work on the Royal Castle (1517-1536) was initially undertaken by Francis of Florence, but later the construction continued under the supervision of Bartolommeo Berrecci following the guiding principles of his compatriot's design. This latter Italian added a gate building (1533-1535), whose portal makes allusions to a triumphal arch.

The castle consists of four wings, the southern one being just a galleried curtain, combining residential with state functions. It is embellished by a three-storey-high colonnaded courtyard. The two lower stories feature regular arcades, and the third, the highest situated under the extending eaves of the roof, is given slender proportions acquired thanks to the doubling of the column height. This design is an excellent example of a multi-story arcaded courtyard built outside Italy. It follows the Renaissance idea of unity of composition with refined and light proportions allowing the design to achieve an unusual, elegant character.

The rhythm and regularity of the whole were retained, while much of the original, damaged stonework was either reworked or exchanged during the restoration works. Experts note that there have been significant changes in the Renaissance decor of the courtyard. For example the original colours disappeared from elements of the architecture: the column shafts, today in the colour of natural stone, were royal purple in the 16th century, and their capitals were most probably gilded. Continuing along the gallery were decorative frescoed friezes, a section of which depicting busts of Roman emperors has been preserved in the eastern and southern wings. Full of colour, the courtyard was a proper setting for the life of the royal court, magnificent celebrations, spectacles, and knightly tournaments.

Its current state is the result of restoration work which was intended to restore the appearance of the royal residence to that of its heyday.

The castle contains regal state rooms in its eastern and northern wings. Most of them have been restored to the decor of the days of Sigismund the Old and Sigismund August. The largest of the rooms, the Senators Hall, was originally designed for the sessions of the Senate, major ceremonies at court, balls, and plays and spectacles. In 1518 it provided the setting for a royal wedding, that of Sigismund I and Bona Sforza, for the first time. Its walls are decorated with huge figurative tapestries on subjects taken from the Bible, which belonged to the collection of King Sigismund August.

The Audience Hall was designed for the sessions of the Sejm (Lower House of the Parliament) in which the king participated. In the first half of the 20th century the chamber had its coffered ceiling reconstructed, and 30 heads sculpted in 1540 by the workshop of Sebastian Tauerbach and Master Jan called Schnitzer were returned. The original ceiling housed 194 sculpted heads, but it was destroyed early in the 19th century. The contemporary arrangement of heads is random. The preserved specimens support the claim that the sculptures represented people contemporary to the artists: not specific individuals but rather human types: burghers, courtiers, soldiers, as well as literary and mythological figures, which may be connected to the Renaissance thinking about portrait being strongly set in individualism. The Renaissance decoration of the hall, apart from the tapestries, consists of a wall frieze presenting The History of Human Life, an illustration of the antique Tabula Cebetis, and portraits of King Sigismund the Old and his daughter, Anna the Jagiellonian.

The Tournament Hall is adorned by a wall frieze painted in the 1530s by Hans Dürer (Albrecht's brother) and Antoni of Wrocław. Renaissance paintings by Italian artists are exhibited here; of particular note are portraits of members of the Medici family painted by Alessandro Allori and Giorgio Vasari. A Siena table from the Palazzo Palmieri is worth mentioning from among the Renaissance furniture.

The most precious element of the exhibition in the Renaissance chambers, and the only one to be preserved from the original furnishing, is the collection of tapestries woven in Brussels to a commission of Sigismund II August. Made to the design of Dutch artists, they represent the highest artistic standard. They are woven from cotton, silk, silver, and gold threads, with the fineness of the weave ranging from 7 to 8 threads per centimetre). The collection made for the Polish king from around 1550 to 1560 includes 138 preserved pieces (although originally there could have been around 170). It consists of a number of series on varied themes, of different sizes and formats, made in various workshops.

The biblical series is composed of 19 huge tapestries presenting scenes from the Old Testament. The designs for the tapestries were made by Michael Coxcie (1499-1592), a Dutch painter and the main representative of painting based on the achievements of the mature Italian Renaissance. The borders filled with ornamentation, known as Dutch grotesque, which frame the central field of every tapestry were designed by an unknown artist from the circle of Cornelis Floris de Vriendt (1514-1575) and Cornelis Vos (1506/10-1556). The series of landscape and animal tapestries, known also as verdures with animals, consists of 44 representations of the fauna against landscape backgrounds, and is a reflection of the interest of Renaissance people in nature and the world around them. The series of tapestries with coats of arms of Poland and Lithuania, and the monogram of Sigismund II August - SA consists of a number of types of heraldic representations displayed against Dutch grotesque.