Rock and roll! I totally agree with KMadCandy, it's great when you get asked for some crap old tech that you couldn't sell for beans, it's essentially a free +1 diplo for a while, and how much research did you save him, anyway, four turns? You don't want to deal with a grumpy Mehmed right now, so no harm done. I'd forget about the great library. You're financial, so you'll be pretty steady in research anyway, and right now you need to focus on wiping that Mongorian off the map before he can upgrade his archers. If you're not sure you'll catch it anyway, is it really worth the diversion? Also, keep construction to yourself for now. Mehmed isn't trustworthy, and soon you'll have a giant pile of freshly conquered cities that he'd probably love to take off your hands if he smells opportunity. Isabella will warm up soon enough. It's almost too bad that Mehmed didn't found Confucianism and alienate the Spaniard. I too agree with Validator on the keep/raze cities. Might be good to keep a settler handy, though, if Mehmed starts poking his nose in where it doesn't belong.