I’d love this, would be cool - perhaps wonders generate tributes from gaia on top of that similar to a feitoria function - I’d say make it worth 2-3 feitorias with no population cost(the build time as well as the location being visible by all is cost enough alongside the resource cost of the building alone) of course limiting the amount of wonders to 1, as well as give a different bonus for each civ.
For instance:
Aztecs: Relics Generate 200% more gold, Jaguar Warriors +1/2 armor and +2 attack
Berbers: All units move 10% faster
Bohemians: Monks cost -50% resources
Britons: Archers +1 attack
Bulgarians: Cavalry + 5 attack
Burgundians: Relics generate 5 food for every 1 gold and vinyard gold generation is increased by x3 as well as relics now generate 2 wood for every 1 gold
Burmese: Battle Elephants +30% speed and +4 attack
Byzantines: Cataphracts +2/2 armor and -33% cost.
Celts: Woad Raider +12 building attack and +2/4 armor and castles/towers and town centers fire 50% faster.
Chinese: Scorpions and Chu Ko Nu + 2 range
Cumans: Kipchaks +1/1 armor, +10% HP and +2% movement speed
Ethiopians: Shotel warriors + 1/1 armor, +10% hp and +2 attack
Franks: Throwing Axemen +2 attack are effected by ballistics and +1 range
Goths: Unlocks final armor upgrades for infantry and cavalry as well as arson. Huskarl +10% movement speed.
Huns: Tarkans +4/1armor, +8 building damage.
Incas: Villagers and melee infantry units + 2/2 armor and +7% speed
Indians: Villager cost -50%, gain sappers and work 10% faster
Italians: Infantry and Genoese crossbowmen +3/1 armor
Japanese: Samurai +10% movement speed, +1/1 armor, +10 bonus damage vs unique units.
Khmer: Villagers no longer need resource drop off points, and Elephants +10% movement speed
Koreans: Siege Weapons cost -50%, and unique units +10% movement speed, +1/1 armor
Lithuanians: Unique Units +2 attack and town centers +3 range, +4 attack
Magyars: Stable/castle and cavalry archer units -20% cost
Malay: Karambit warriors and militia line cost -50% resources and gain +10% movement speed.
Malians: Town Centers fire x2 arrows and Gbeto +2 attack
Mayans: Eagle Warriors cost -30% resources
Mongols: Cavalry Archers and stable units attack 25% faster
Persians: War Elephants +20% movement speed and cost -20% resources
Poles: Knights deal Trample damage and cost -60% food
Portuguese: all units cost -20% resources
Saracens: Market Trade cost is 0%, and Mamelukes +3 attack, +1/1 armor
Sicilians: Upon finishing the wonder all town centers (up to 10) spawn a group of 7 Elite Teutonic Knights, and all castles (up to 4) spawn 10 Crusader Knights
Slavs: infantry +2/2 armor and +2 attack
Spanish: Conquistadors x1.5 attack speed, +1/1 armor
Tatars: Keshiks x2 gold generation and +3/0 armor.
Teutons: Monks heals up to their own line of sight and Teutonic knights +1/3 armor, reduced pause time between switching targets to heal
Turks: gunpowder unit resource cost -30%
Vietnamese: Rattan Archers +10% hp, +1 attack, and +1/3 armor
Vikings: Increased Berserk Regeneration speed by x2, +2/1 armor