I don’t know if it’s true of other science fiction writers, but I’m fascinated by ancient history. 
For me that means Roman and earlier. Not that I’m any sort of scholar on the subject, I dip in and out rather at random. Reading about the ancient past helps me when trying to imagine future lives and societies on alien worlds. When you read or write science fiction, you put yourself there, imagining it, trying to see those worlds and feel what your characters are feeling. Ancient history is the same for me.
The fascination is that ancient worlds are alien worlds in many ways, but ones we can still connect with. You can walk the streets of ancient Rome, Pompeii, Troy, Mycenae and Luxor. 
You can see something of where and how they lived and imagine the lives of those people thousands of years ago. It’s something familiar yet very different. The world of ancient Egypt is so ‘alien’ that it has been incorporated directly into recent science fiction on a number of occasions. Then there’s the impact the Romans or Greeks must have had on peoples meeting them for the first time. The way ancient Britain’s felt encountering the Roman legions must be similar to how we’d feel if spaceships landed and strange beings emerged .
It also tells us that what forms the basis for our current society and how people live is much the same as it was thousands of years ago. The past may seem more brutal, perhaps in some ways it was more honest. However, most people in the ancient world were just trying to get along, hopefully better themselves and enjoy whatever of life’s luxuries they could get their hands on. No change there then. Then at the top it’s all about the desire for power and wealth with some love and lust thrown in. Seem familiar? Replace armies, assignations and what seems to us, cruelty (not that it doesn’t exist in our world) for big business, takeovers and the boardroom. We even talk about the cut and thrust of business. So when I imagine the societies of the future I see much the same things driving them. Ancient history provides inspiration for ruthless characters, plots, and the building of empires.
So if you haven’t dipped into the ancient worlds, I recommend it. If you want somewhere to start here are a few to try: There’s the Simon Scarrow novels (already in ‘Inspiration’), following the lives of the two centurions, Macro and Cato; David Gemmell’s Troy series; Conn Iggulden’s Emperor series. I loved the Allan Massie book, ‘Augustus’ which gives a vivid account of the life of first Emperor , Caesar Augustus, the politics and the ruthlessness of his rule. 
Interestingly, it paints quite a different picture to the scheming, poisoning Livia of Robert Graves’s ‘I Claudius’. On the non-fiction side I’ve recently read ‘Rubicon: The Triumph and Tragedy of the Roman Republic’ about the life of Julius Caesar and ‘Ancient Rome: The Rise and Fall of an Empire’ by Simon Baker. Both are very readable. If you have others to recommend let me know.
