I have looking around the past threads and I noticed that here, in AH.com, we have so many questions that we either can't give a satisfying answer or can't come into agreement over the rightful answer...
So I decide to make this thread, in order to gather those unanswerable questions (and maybe we can finally get the answers)...so feel free to expand the list...
1. Had Alexander gone west instead of to the east, could he defeated the Roman legions?
2. Were the Romans willing and able to conquer Germania, and would the conquest prevent their decline and fall?
3. Could the Carthaginians build a Mediterranean Empire just like the Romans did in OTL?
4. Was it possible for "Hero's engine" to be developed by the Romans to become a fully-functional steam engine?
5. Could the Celts developed into a unified empire/kingdom in the absence of Rome and repelled the Germanic invasions?
6. Was there any relationship between Christianity and the Decline of Roman Empire?
7. Could the marriage between Charlemagne and Irene unified the Franks and Byzantines?
8. Could the Holy Roman Empire developed into centralized state?
9. Was it possible for the Mongols to conquered Central and Western Europe?
10. Was it possible for the Vikings or Ming Dynasty to discovered the New World and colonized it?
11. Was it possible for Qing Dynasty or Ottoman Empire to industrialized and modernized themselves?
12. Was it possible for Napoleon to won the Napoleonic War and built a lasting empire?
13. Was it possible for the Confederate States of America to won the American Civil War and became a great power on its own?
Is there anything that I missed?