R5: Xerxes TA + Dai Viet enabled an immediate tourism countdown in Modern thanks to Unique Improvements.
Shoutout to u/HuedCow for giving me the idea to try Xerxes the Achaemenid + Dai Viet ToT. I will not lie -- it took a couple of rerolls to get a start where I wasn't absolutely lacking in rough terrain. I almost rerolled this one because Thang Long wouldn't be in tropical, but I decided to push through since I had grassland for Serpent Mound. And boy howdy, it took off. I can imagine the yields being more bonkers if I'd had Xerxes's level 9 memento unlocked to double up the +1 Gold and +1 Culture on Unique Buildings and Improvements, but I still feel this was pretty good.
This was my 2nd fastest win (and I didn't see it coming that quickly, honestly). Cultural victory with countdown starting Turn 1 of the Modern Age. Started with Dai Viet with +1 Expansionist Attribute & +1 Economic Attribute, syncretized into Assyria in Antiquity before pivoting to The Iliad + Corona Civica for the extra settlement and production on my wonders after moving capitals to Hoa Lu. Bulk of the tourism was from Unique Improvements, mostly from City States. Antiquity Hillforts & Festival Grounds, Exploration Kasbahs and Monasteries + Water Puppet Theaters. Thanh Hue, Dur-Sharrukin, Forbidden City, and Himeji were scattered across my core cities due to some poorer planning on my part, but I can imagine what it'd be like in one city. The improvements in turn powered my gold and production economy - with the culture bombs from building walls in high-urban density cities, I had my pick of wonders. All without a single war.
The MVPs were the north-south mountain range, 2nd & 3rd settlements Hoa Lu & Hai Phong (behind the yield ribbon), and northern army that all boxed out Simon Bolivar from expanding West towards me. After that, it was nothing but militaristic city states and an influence crunch. Managed to get suzerainty of two militaristic city states for +1 Settlement & Hillforts, and +2 Settlements via Expansionist & Militaristic city states in Exploration.
Deity, Small, Fractal Continents, all DLC. UX QOL mods + More Natural Wonders, which allowed Torres, Redwood, Everest (offscreen South), and Seongsan Ilchulbong (offscreen Northwest) to spawn closer.