Like Jno said, the move from Milan to Ravenna was part and parcel of the last rulers of the western Empire feeling under pressure from invading armies. Ravenna's site resembled that chosen by the Veneti at around the same date - became Venice.
So, marshy coastline, lots of mosquito swamps, hard to march an army over. also, down the coast a couple of miles was the mighty port of Classis, so not too isolated from essential arteries of communication.
Ravenna was pounded to shreds during the Allied advance in 1944,so a lot of the town is sort of 1960s. It is blisteringly hot in summer. I enjoyed visiting it and wandering round. There's a hostel that provides brilliant accommodation, and good train links although not the fastest line.
As well as the remains of churches and baptistries with mindblowing glass-tesserae mosaics, there is the wonderful mausoleum of Theodoric just over the railway bridge from the town - worth the walk. Enjoy the amazing acoustics inside it.
And excavations are still going on at Classis, so you could enrol and get first hand experience of the past.
I apologise for the general snootiness of some other replies and hope you'll post more questions.