One of the problems is that, as opposed to the Calvin book, we don't have portraits of Augustine done by his contemporaries, and we don't have any buildings from that time still standing - just ruins. In Milan, we have less than that, because the city was totally destroyed by Barbarossa in 1162.
A second problem is time - most of the photos on wikimedia and other free sources online have a low resolution, and where am I going to find lots of photos with so little time left (the book is being typeset and they actually stopped working on it because of this)?
I have been looking everywhere and praying for God to supply.
One of the first answers to prayer has been this photo on the left, sent by James O'Donnell, provost at Georgetown University and author of Augustine: a New Biography, which has been a great addition to my research material while writing my book. James O'Donnell has a wonderful website on Augustine: http://www9.georgetown.edu/faculty/jod/augustine/
This photo shows the remains of Augustine's church in Hippo Regius, with the altar and apse at the far end. I am deeply grateful to O'Donnell and to God!