Complex sentence: Melitene's city walls were constructed in the 6th century by the emperors Anastasius and Justinian, but those that still stand mostly date from the Arab period, perhaps of the 8th century, though retaining the layout of and some remnants from earlier building phases.
Split into simpler sentences: Melitene's city walls were constructed in the 6th century by the emperors Anastasius and Justinian. Those that still stand mostly date from the Arab period, perhaps of the 8th century, though retaining the layout of and some remnants from earlier building phases.