What Civ-unique improvements need a buff?

For example, the Kurgan is widely accepted as one of the worst unique improvements in the game. How would you buff it?

 

Just make it so that it gives Tourism equal to its Faith Yields, or make it give extra Yields to adjacent Pastures.

Also, welcome to the CivFanatics Forums, @Arenn21.

 

Not entirely sure when it comes to improvements... I mean, the Ziggurat can be good early on but quickly drops off and becomes a dead tile. Maybe give that some better scaling? Unless, of course, it's meant to fit with Sumeria's theme of "insane early game, intentionally bad late-game" due to them being the first known civilization (historically). In that case, I'd keep it.

I know the Roman Fort is pretty bad, but I'm unsure if it can really be considered a unique tile improvement. Getting this out of the way though, the Roman Fort is bad, but that's because forts as a whole are bad. The thing that really confuses me about the Roman Fort is that- according to the wiki- it doesn't even function like a unique tile improvement. Quote from the Roman Fort's wiki entry: "It does not count as a unique improvement or grant +4 Era Score when built, nor does it trigger the Eureka for Ballistics."
At least for consistency's sake, if you're going to give it a different name, give it the full unique improvement treatment. Give the Roman Fort era score upon building and make it function properly (even if it isn't considered a unique improvement, it has no reason not to trigger the Ballistics Eureka).

And can someone who's played more of India tell me if the Stepwells are any good? They seem a little underwhelming just looking at their stats, but I'd like to know if they could be better in practice.