If you're ever roaming aimlessly south of Venice and east of Bologna, Ravenna is a pleasant place to spend an afternoon. It was actually the capital of the Roman Empire for much of the 5th century. It is best known now for its collection of early Christian monuments. The centerpiece of those monuments is the Basilica di San Vitale (buttress shown here).
Getting into the basilica is more challenging that one might expect as you first have to enter a museum, buy a ticket (get a combination ticket!) and then find your way back around the museum to the basilica. There's sort of a one-way path through all of this. The basilica was consecrated in 547 AD and the chancel is completely covered in mosaics.
This mosaic depicts Abraham, three angels and the sacrifice of Isaac.
The Byzantine Emperor Justinian made Ravenna the western capital of his empire and he is depicted all over the city. An interesting reflection on the politics of the time, the center figure here is Justinian. Maximianius, the bishop of Ravenna holds the cross and has his name somewhat ostentatiously lettered above his head, just in case anyone might not recognize him apparently. In between them is the banker who financed the building of San Vitale.
Behind the church is the dimly lit mausoleum of Galla Placida (half-sister to Emperor Honorius) which contains more mosaics.
Across town (which means a ten minute walk) is the Neonian Baptistry which started out as a Roman bath and ended up (so far at least) as part of the Ravenna monument tour with an impressive mosaic of the baptism of Christ above the font.
Also located in Ravenna is the tomb of Dante Alighieri who was exiled from Florence in 1302. At least part of his Divine Comedy was written in Ravenna. We found it slightly disappointing that it does not say 'Abandon All Hope Ye Who Enter Here' above his tomb. The tomb may be open periodically but it seems impossible to tell when that might actually be.