In this four-part series exclusively available to subscribers of HistoryExtra, Dan Jones talks us through the four ages of medieval history, from the decline of the Roman empire in the 5th century through to dawning of renaissance ideas and the religious revolution in the 15th and 16th centuries. On the way, we criss-cross western Europe, considering Franks and Arabs, Mongols and monks, Crusades and pandemics and much more besides.