The arrival of the Royal Opera House Muscat in 2011 was a high point in the cultural life of the capital. Built by the same architects as the Grand Mosque, the understated marble exterior belies the magnificent interior of inlaid wood and Arabesque designs. Some of the most famous names in opera and ballet performed in a world-class program in the opera house's inaugural year and the quality of production has already won international acclaim. There's a strict dress code for attending a performance: jeans are not permitted. Even if you're not intending to catch a show, it's worth stopping by to admire the beauty of the building and enjoy window shopping in the adjacent Opera Galleria arcade. Call the box office to check the availability of tours.