The famous Zagreb Cathedral is the tallest and one of the most beautiful buildings in Croatia and attracts thousands of tourists worldwide. As the most impressive gothic-style sacral building southeast of the Alps, it is characterized by great architectural and historical value. Its construction dates back to 1093, with continued enrichment of the cathedral by famous architects during the following centuries.

Reconstruction of the cathedral in the late 1800s was led by Hermann Bollé, who brought the cathedral to its most recent architectural form in which it stood until the earthquake of March 22, 2020 when the cathedral’s southern spire was damaged. Over the last 30 years, extensive restoration work has been undertaken on the cathedral, with ongoing repairs to this day. During reconstruction work on the south tower of the cathedral in 2012, damaged steel joints were found surrounding the tower 4 inches below the surface at approximately every 1.1 yards between the first and 25^th rows. Most of the joints were only partially exposed in order to replace the surface layer of stone on the belltower, while the back of the joints remained embedded in stone and lime mortar. The joints were covered with a layer of rust and, in drainage areas, corroded all the way through the cross-section. In order to define the optimal solution for maintaining or improving the mechanical resistance and structural stability of the tower, the faculty of mechanical engineering and naval architecture of Zagreb was called in to examine the joints.