Hello! Sorry if this has already been suggested. I simply couldn't find the search function in the forum so I didn't have an easy way of checking.

The "Can only be built once per empire" tooltip should be a little more prominent. I tried to build the Denarque University in several systems without noticing that it was a unique system improvement that could only be built once. I caught on quickly when the build queues suddenly indicated that they'd take infinity to complete the thing in every system I had it building. Still, it was a lot of turns wasted on building something I wasn't going to get in any system but one.

Yep, I've generally kept an eye out for it, but with the amount of information being shot at new players, probably wouldn't hurt to just have the game straightup remove it from the selection menu once it's already being built/is built elsewhere.