 There are several references to the cathedral in medieval sources . The earliest reference to the church tells of the transfer of Saint Michael the Warrior 's relics from the <unk> fortress to the Patriarchal Cathedral on the order of Tsar <unk> ( r . <unk> – 1207 ) . The housing of a warrior saint 's relics in the Patriarchal Cathedral signifies the incessant warfare against <unk> and <unk> that dominated <unk> 's reign . In the late 14th century , the last Patriarch of Tarnovo , Saint <unk> , described the church as the " great patriarch 's Cathedral of the Holy Ascension " in his writings . 
