We went to the Sheikh Zayed Grand Mosque in Abu Dhabi, and got lucky enough to arrive just as a tour was about to start.  I would recommend taking it if you get there in time, it was interesting and informative and well done.  Visiting hours are 9am to 10pm daily, except for Fridays which start at 4:30pm.  The tour is 45-60 minutes and is available in English and Arabic.

On the tour you learn of the construction of the mosque, one of the things I found really interesting was that the entire carpet is one single piece!

Also very interesting to see was how the mosque (completed in 2007) looks in comparison to the much older mosques in Turkey.

There are lots of videos of the mosque on youtube that have lots of information; I think this one is pretty cool because the video is good but also this guy was our tour guide!

Here are some snippets of video from my visit; I think I may be the first to post any 4K footage? Highly recommend a visit if you’re in town.