Sounds kinda like CTP2, first to sail around the world, feats of the world thing. I don't see how a great building indestructable though.
Scientific projects should use all cities that have research labs and even if you lose all the labs once you build some more you can start up research where it was lost. Maybe once the UN is built after say 20 or so years the project would be known to all civs at that tech level(these aren't weapons techs and how long is someone going to keep the cure of cancer secret).
social projects
Social projects would be started by government laws or promotions (promoting idea). ie emancipation would free your slaves and hurt slave countries(if we have slaves in civ3). Social projects should tie in with other countries, great society helps countries with high socialism levels(country is socialist, read the mass media thread) stuff like that. Social projects can help all, help u hurt everyone else, help you hurt certain civs. Certain couldn't be done by all government had to be promoted like MMM.
First projects
If we have tourism(I hope) the city were the ballon or air or ship was from would get extra tourism. If your civ climbs the highest mountain then people will come to your civ to help them climb. First projects could be started promoted by government but not done, specifically you have to convince some of your people to do it.
Example
New York City flies ballon around the world. People from all over the world come to new york to see the balloon mueseum balloon festival and other nyc sites. NYC gets extra money which can buy improvements/units/expand systems(my idea). NYC can get visa taxes also.
Beijing climbs highest mountain even though it is in india. People come to beijing before climbing to get expert beijinger climbers to help. Beijing gets tourism and visa taxes from tourists.
Visa tax is just a name for taxing foreigners I know you don't tax visas in real life.
------------------
I use this email
(stupid cant use hotmail)
gamma_par4@hotmail.com
Don't ask for golf tips
Your game will get worse