I'm reading two different books about two very different sorts of empires - "Osman's Dream", a history of the Ottoman Empire, and "Empire Express", which covers the building of the transcontinental railroad in the US.

"Osman's Dream" covers the span of the Ottoman Empire (and a few years after it's fall) - a very long sweep of history. I'm only a little way into that book - some of the events are already familiar to me from my reading about Tamerland and the Baghdad based Islamic Caliphate.

"Empire Express" covers the much shorter span of time from the late 1850's, when the idea of the transcontinental railroad got seriously floated, through to it's completion in 1869. The amazing thing is that construction got started during the civil war - the author notes the incongruity of crucial business meetings happening at the same time as the Batlle of Gettysburg. This is also a huge book, and since I'm reading it in snatches before bed, I'll be at it for awhile.

Those two should keep me busy for a bit :)