The city of Varaždin began its development during the 12th century. Next to the royal fortress as the backbone, a market town developed, inhabited by immigrants (hospites), mostly of German origin. From the very beginning of the development of the city until the middle of the 19th century there were two administrative units in the area of today's Varaždin - the free royal city of Varaždin whose inhabitants were free people, and the Varaždin old town municipality whose inhabitants were subjects of the fortress. In economic and urban terms, these two administrative units were developing together and intertwined at the intersection of traffic routes, which resulted in the presence of different cultural influences. In the 15th and 16th century Varaždin was urbanistically divided into the "inner" part of the city, the core, surrounded by defensive walls and ramparts, and the "suburbium", the suburbs, unprotected from possible war dangers and attacks. Research has revealed that during the 16th century, the urban ensemble of Varaždin got its recognizable present-day identity. In the city center, a new rectangular square was formed with the Town hall as the main accent, and it became the municipal center of the city. During the 15th and 16th century, Varaždin was historically and artistically enriched with important architectural and artistic achievements that bear the hallmarks of the styles that prevailed in Central Europe at that time. With this dissertation, these achievements are presented and valorized. While exploring the sacral buildings, it was discovered that during the 15th century renovation and reconstruction of the parish church of St. Nicholas a late Gothic stylistic expression was used. It was concluded that the restoration of the church, carried out at the end of the 15th century bears the signature of the two most important donors - the royal, with the Corvinus coat of arms carved on a keystone and the municipality with the coat of arms of Varaždin carved on a stone and built into the church tower. Furthermore, the Varaždin fortress Stari grad was explored. It is the most layered building complex in the area of Varaždin with preserved construction interventions from the 13th to the 20th century. The construction phases of the 15th and 16th century, when the medieval fortress was transformed into a Renaissance fortified residence were researched, and are valorised and presented in this dissertation. The preserved constructional layer of the 15th and 16th century in the communal, public and residential architecture of the city has been researched and valorized. Preserved civic houses from the 16th century all belong to the same type of spatial organization and follow the Central European Renaissance trends in the construction of urban architecture. During the research, several builders and stonemasons stood out as typical representatives of the style that prevailed in Central Europe at the time. The construction and stonemason's workshop in the service of Herman Celjski left a significant mark on two construction sites in the city in the first half of the 15th century. On the southern square tower of the Varaždin fortress, they left their signatures in the form of stonemason's signs, while on the town hall the authorship of the same workshop is assumed on the basis of stylistic analysis. Domenico dell'Aglio as the leading name of the Austro-Italians left a significant mark on the transformation of the Varaždin fortress which, for the most part, preserved his Renaissance design to this day. His successors and associates Juraj Flajšman and Giovanni Aglio, who remained to work in the city of Varaždin, are the stylistic authors of a number of civic houses in Varaždin.