The Byzantine Empire was one of the great human achievements that endured for a thousand years. Its influence on the modern world has been greater than commonly supposed.
I found an old copy of this, looks like it could have been written in 1453. Typical take on Byzantium - too little focus on the greatness and too much on the decline.
Really informative general overview of Byzantine history and culture. Very readable; the text flows well. Although it is old (1919) apparently most of the scholarship is still regarded as solid. Not knowing much about Byzantium, it seemed to me the next logical step after steeping myself in Greek and Roman history for so long. I was not incorrect - as the heir to the Roman Empire it offers much fascinating history to learn about. Its identity as Imperial, Greek, and Orthodox defined the policies and priorities during the life of this great civilization. It often seems to be forgotten about in the general public, but Diehl does a good job of showing how Byzantium influenced peoples and nations while it existed and after it perished. Justinian, the Isaurians, the Macedonians, the Comneni, the Palaeologi - a fascinating bunch. Constantinople fell in 1453, but the legacy of Byzantium lives on.