For opera we have opera house. Art gallery is another thing which shows oil paintings and sculptures and such. Which under fascism and generally non-democratic society whould fall in line with ruling ideology and/or religion. And even in democracy you cannot publicly present art which might be considered as racism or harassment for example.
I agree with DH here, for game balance sake, because from later medieval and further on we have MASSIVE inflow of culture, WAY too many +30%, +50% etc buildings and religions spread widely by that moment. Cities grow legendary at the late industrial/early modern phase without moving culture slider or turning city output to culture. And all my cities go 3 tiles in the reneissance. I would say culture needs tuning down abit taken fact we have so much buildings and majority of them have culture bonus built in. While balanced in prehistoric-classical stage, that gets out of control later on as i said. I always turn off cultural victory in my games now.
Also, while at that please take a look at cathedrals - Confucian academy needs single temple as requirement to be built.
2Koshling - new AI combat is better than before, it no longer sits before cities forever, however after engineering (and castles which have castle gatehouse preventing to enter until defences are down) i noticed Justinian declare war at Bismark, move his stack of doom (200+ troops, including some heavy cannons) to neighbour city and move back and forth not taking down defence from city (it was 140%). Bismark had like 10 troops inside city, weaker then attacking units.
If you want i can upload savegame.
Also, about new times for peace treaty. I play on snail, it is 60 turns here. While 10 turns was too fast, 60 turns is ALOT, especially at later eras, where techs get discovered around 3-5 turns each. My opinion would be halving that to 30 turns.
p.s. I saw Hitler paintings, they were not that bad, but nothing outstanding. Something every student of art college would paint. IMHO