I recently uploaded a new Civilization V mod onto the Steam Workshop. The new mod adds a National Park building that is unlocked with the Scientific Theory technology. The National Park can be built in cities that contain natural wonders, and the National Park will provide bonus Gold, Science, and Culture to all natural wonders within the city radius, as well as provide 3 global happiness.
National Park building adds gold, culture, and science to all natural wonders within the city,
as well as providing 3 global happiness.
I am considering updating the mod so that the building requires the Railroad or Combustion technology instead of Scientific Theory. Scientific Theory already provides plenty of science bonuses (obviously) including allowing two scientists from the Public School building. Putting the building in Railroad or Combustion would give that tech a non-military bonus and add an opportunity for civs focusing on the lower half of the tech tree to be able to get some extra science (if they have natural wonders). Also, from a historical standpoint, prior to the invention of trains and cars, not very many people would have been able to travel to enjoy the benefits of national parks, and so placing this building in one of those techs would emphasize the tourism and travel benefits that those inventions provide.
In addition, once the Brave New World expansion is released, I will likely update the building to include a heavy tourism bonus.
The mod is available on MegaBearsFan's Workshop, and can be downloaded on Steam or via Civilization V's in-game mod browser.
UPDATE (July 18, 2013 9:35 PDT): National Park updated for Brave New World expansion
I have updated this mod for the new Brave New World expansion. If you have BNW installed, the National Park will now be unlocked with the Railroad technology, and the building will improve the Tourism output of your city.
National Park building updated for Brave New World to be unlocked with Railroad and add +25% of the Culture from wonders and improvements as Tourism.
If you are still playing Gods & Kings, the mod does not change the prereq or functionality of the National Park for that expansion. Updating the mod should not affect saved games for G&K players.
Thanks for playing, and enjoy!
UPDATE (July 24, 2013 10:30 PDT): National Park changed to provide +5 tourism instead of percentage modifier
Version 4 of my National Park mod has been published. The update changes the 25% conversion of culture to tourism so that the building provides a static +5 tourism. This was accomplished by using the TechEnhancedTourism and EnhancedYieldTech properties so that Railroad (the unlocking tech) adds +5 tourism to the building. This is the same method that is used for the Eiffel Tower world wonder.
National Park building updated for Brave New World (version 4) to add a flat +5 Tourism.
This was done so that the National Park will always provide a substantial tourism output to the city (equivalent to 2 1/2 Great Works), regardless of how culturally strong the city is. Since many Natural Wonders do not generate large amounts of culture, I couldn't expect that a city containing the National Park would necessarily have enough culture for the 25% conversion to be worthwhile.
The only major downside to this change is that the Airport and Hotel don't synergize quite as well with the National Park. Aw well, can't be perfect, I guess...
UPDATE (March 5, 2014 11:15 am PST): Yields of BNW natural wonders fixed
Apparently, I had neglected to include yield modifiers for the new Brave New World natural wonders (King Solomon's Mines, Lake Victoria, and Mt. Kilimanjaro). I have just uploaded a revision that addresses this issue so that all natural wonders in the game now include the bonus culture, gold, and science from the National Park building.
This fix is available in Version 5 of the National Park mod.
I did discover one other issue: it appears that Isabella's trait ("Seven Cities of Gold") does not double the bonus yield provided by the National Park. It seems that the core game does not check the Buildings_FeatureYieldChanges table when applying Spain's trait. This will likely require an update to the game DLL, which I do not have the time to implement at the moment. I hope to be able to update the mod to address this issue at a future date.