The Grand Mosque in Muscat (Oman) is one of the “must see” spots of the city. The best times to photograph are at dawn and dusk, but these do not overlap with public visiting hours (8 – 11 am). So, when the light is more interesting, you are limited to take photos from the outside; this is still interesting, and makes for some nice photographs.
To photograph the interior of the Mosque, as well as its environs (gardens and surrounding complex), it is better to arrive at 8 am, to still have some interesting light (during winter), and avoid the crowds. Inside the Mosque, there is a pathway that you must follow, but still, some interesting photos can be taken. Also worth documenting are the various archways (which provide interesting viewpoints) and the several styles of ceramic tiles. It makes for a very interesting learning and photographic experience. A wide angle lens, or wide angle zoom, is recommended to photograph the Mosque.
At the end of the day, you can then relax and unwind in the beach front of the city, even trying your luck at football!