Gold: see above
Food: granary>water mill>acqueduct>hospital>medical lab
Science: library>university>public school>research lab
Culture: monument>amphitheater>opera house>museum
Production: water mill>stable>forge>workshop>factory
Military: barracks>armory>I think it's called a military academy?
Defense: walls>castle>arsenal>military base
Trade: caravansary>harbor
Faith: shrine>temple
Sea resources: lighthouse>seaport
Happiness: circus>colosseum>zoo>stadium
This is all I could think of/remember. In some of these there are subgroups, for example the food category has both a food improvement class and a food storage class; additionally, you could look at there being a sort of overlapping subgroup of "tile improvement" buildings, which would include granary, stable, forge, lighthouse, and seaport. Forge and stable are unique in that they can only be built in range of certain resources, as is the circus.