The wiki contains lists of science and city improvements and units, but I don't really see a list of unique world buildings, those that can only exist once in the world.

From the science screens ingame I can often read the desription, but I was hoping there was a list on a wiki somewhere that I missed?

What I find strange is that the list of city improvements dont contain any world unique improvements, nor does the science page list any, even though some of those sciences directly allow one such building?

If you are talking about unique buildings like the Aurigan Museum of Science, then those are unlocked as you unlock eras in science. Note that they will not appear if another race has built them already.

Ah, legendary buildings. Thanks for the help guys!

You're welcome.