Built in a Renaissance-Gothic style and constructed over the site of an older fortification on a rock above the small Zlaști River, the castle is a large and imposing structure with tall towers, bastions, an inner courtyard, diversely coloured roofs, and a myriad windows and balconies adorned with stone carvings. The castle also features a double wall for enhanced fortification and is flanked by both rectangular and circular towers, an architectural innovation for the period's Transylvanian architecture. Some of the towers (the Capistrano Tower, the Deserted Tower and the Drummers' Tower) were used as prisons. The Buzdugan Tower (a type of mace after which it was named) was solely built for defensive purposes and it had its exterior decorated with geometric motifs. The rectangular shaped towers have large openings to accommodate larger weapons. In the castle yard, near the 15th-century chapel, there is a well 30 meters deep. According to the legend, this fountain was dug by twelve Turkish prisoners to whom liberty was promised if they reached water. After 15 years they completed the well, but their captors did not keep their promise. It is said that the inscription on a wall of the well means "you have water, but not soul".
The Guaita is the castle in San Marino that was built in 11th century.