While in old town, I went to see the museum of illusions. I've seen other ones like that before, it's not a must go attraction, but it's fun to visit if you're in the area. I was, so I did:
On my 2nd day in Abu Bhabi, I went to see the Louvre that opens at 10:00, not super early, but nothing opens early in UAE. It's not like the Louvre in Paris obviously, that louvre you can barely do in a very long day, but the Abu Dhabi one can be done easily in 3.5H if you do everything carefully (what I did), or 2H if you go through it more quickly. It is a beautiful building, definitely worth a visit no matter what:
the section on old Paris from 130 years ago, was really cool
The outdoors were fantastic:
I probably stayed a bit longer than I should have (it made me late for the rest of the day), but things barely worked out.