Why would christian observers be shocked and awed by what they could see at cordoba?

Cordoba , the second largest urban town in Europe is both ruled and conquered by Romans and Muslim. Structures like churches and mosque are witnesses of harmonious relationship of religion in one city. Hailed as one of UNESCO's world heritage site, the city has historical sites like Great Mosque and Roman Bridge that are well preserved. 

Ibelieve it is the 2nd answer, create gardens on all rooftops. let me know if this .

Answertill;