German heritage advocates have accused the Russian Orthodox Church of causing irreversible damage to the 14th-century Brick Gothic church of St Catherine at Arnau near Kaliningrad, especially to its frescoes.

“The… iconography of the painting[s] in St Catherine’s Church in Arnau from the 14th century had not yet been thoroughly researched [and they] are irretrievably lost,” wrote Nicole Riedl, an expert in Medieval wall paintings at Hawk University of Applied Sciences and Arts in Hildesheim, Germany in her report, after she visited the church in July with a group of activists from the German-based Kuratorium Arnau.