The Royal Opera House Muscat was designed by the same architects who did the Grand Mosque and was completed in 2011. Some of the most famous names in opera and ballet performed the inaugural year in a world-class program, and the quality of production has won international acclaim. Tours of the complex were from 8 a.m. to 10 a.m., so of course it was closed the first time we went there. We tried again the next day, earlier, but they had closed for the Ramadan holiday. We went back at night as a consolation prize, but never did get inside.
There is a very chic shopping mall on the grounds that has to be the nicest in Muscat. Instead of buying some exorbitantly priced souvenir, we bought some Nespresso decaf since we were out at home in Riyadh ;-).
Another view of the front of the opera house posted while I was in Oman: