The Chora Church houses the most impressive collection of Byzantine mosaics in Istanbul. Be sure to come armed with biblical knowledge or a guide, because there are hundreds of motifs adorning the walls that are all the more impressive when one can pick them out. The church structure mostly dates from the 11th century, and the mosaics to the 13th. The second hall has a unique story line of the Virgin Mary’s life. Prepare to be awed.