Dammit! I only checked Versailles and Hermitage

. I had no idea that the rush cost varied!

Thanks
Just to complete the list:
Versailles 1/2
Forgotten Palace 2/3
Hermitage 2/3
National Park 2/3
LC - There are two factors affecting rushing
Without (A) or with (B) any hammers invested
Without (1) Kremlin or with (2) Kremlin
A1 is then without hammers invested and without Kremlin
A2 is then without hammers invested and with Kremlin
B1 is then with hammers invested and without Kremlin
B2 is then with hammers invested and with Kremlin
Each pop provides base hammers, just as hammers from tiles are considered base hammers.
When rushing a building without hammers and without Kremlin (A1) you get
20 hammers / population.
When rushing a building without hammers and with Kremlin (A2) you get
30 hammers / population.
When rushing a building with hammers and without Kremlin (B1) you get
30 hammers / population.
When rushing a building with hammers and with Kremlin (B2) you get
45 hammers / population.
These base hammers are further modified when you rush a wonder. The modifier could either be
2/3 (Forgotten Palace)
1/2 (Red Cross)
1/3 (Broadway)
1/4 (UN)
Base hammers for wonders then range from 5 to 30.
Example: Poprush Red Cross without hammers and with Kremlin, and no production bonus
1 pop = 30 * 1/2 = 15 hammers. Red Cross costs 600 hammers => 40 nurses are distributed among the world to repair the war damage we produce
The modified base hammers are then multiplied with the production bonus in the city.
Example: Above Red Cross is rushed without hammers and with Kremling (as above), but the city has a forge, factory, and power. Bonus = 100%.
1 pop = 30 * 1/2 * 200% = 30 hammers. Only 20 nurses are sent.
Worst rush case is then rushing UN without any hammers and without Kremlin in a city with no production bonus:
1 pop = 20 * 1/4 = 5 hammers. It then takes 200 pop to make peace in the world.
Best rush case is National Park in a capital with IW, factory, powerplant, while running bureaucracy, organized religion and state property (bonus 25 + 25 + 50 + 100 + 50 + 25 + 10 = 285 %) with Kremlin and hammers invested:
1 pop = 45 * 2/3 * 385% = 115 hammers.