E.B. Elliott's Horae Apocalyticae, four volumes, fifth edition.
C.H. Spurgeon calls it "the standard work on the subject", and it is, in my estimation, the single best resource on Revelation. It is both an exegetical and historical masterpiece, filled with wonderful and rare information. However, in four volumes, it is an extensive amount of reading. You will want the fifth edition.
There is a relatively inexpensive digital edition available here.
An abridged edition of Elliott's Horae Apocalypticae is available. The advantage: You can get the gist with less reading. However, the loss is significant; most of the persuasive power of Elliott's work is in the painstaking attention to detail. And we are trying to get beyond mere opinion...