It's a Byzantine bronze follis, of the "Anonymous" type c.1000 AD. These can be attributed to specific emperors; if you post over on the Ancients forum, there are some folks there who can provide that level of specificity. This coin (unless it's a variety I don't recognize) is not particularly rare or valuable, but still a very neat piece of history.
I "believe" the first 2 lines on the reverse say Jesus Christ. I have 2 of these that I am still working on attributing so I can't help you much beyond that.
Class A anonymous follis. Cannot tell if A1,2, or 3 easily from pic. The obverse is Christ, the reverse says Jesus Christ Basileus Basile, (king of kings). Lots more info on the ancient threads. Here is a writeup I did for my coin club about the series if it helps: http://docs.wixstatic.com/ugd/e7a338_d898ad37fc6444d6a6cde1b2c18beacc.pdf
One caveat. I learned here a few months ago the Class E is actually a very scarce coin. I wrote this article based upon my experience, having never having a problem getting very nice Class E's for some reason. If you ever use this as some sort of guide, I would write in that change that the Class E is actually a much better coin.
