The church featured ample exterior and interior decoration . While the facades was decorated with arches and ceramic tiles , the interior floor mosaics was made of white , yellow and pink marble as well as semi @-@ precious gemstones like sapphire and porphyry . The interior walls was covered with frescoes and mosaics . However , none of the interior decoration have survived . During the church 's 20th @-@ century reconstruction , its interior was repainted by artist Teofan Sokerov , who depicted important moments of medieval Bulgarian history in a modernist style . Due to these murals , the church have never been reconsecrated and remain inactive . The facade of the cathedral also include a stone with a donor 's inscription of a Bulgarian ruler , which ended up as part of the building material .