Constructed during the period when the Bulgarian Empire ruled over the town, many experts claim that this massively important church dates as far back at the end of the 9th century. Yet another Orthodox building that once suffered the fate of being turned into a mosque at the hands of the Ottomans, the beautifully preserved frescos inside date from between the 11th and 13th centuries. Such is the importance of the building that you’ll find it reproduced on the back of the 1,000 den banknote.