The first part of the day-by-day route, free to read.
Days 0 to 1: Muscat
Muscat International Airport (MCT) handles most international arrivals. The city is spread across a series of coastal bays divided by mountain headlands; there is no dense urban core in the European sense, just neighbourhoods strung along the water and the main roads. Uber works reliably from the airport.
Book your 4x4 before arriving. There are not many rental companies offering vehicles capable of both the desert and mountain sections of this route, and good cars with rooftop tents are the first to go. The most practical setup is a 4x4 with a rooftop tent and camping gear included in the rental; this eliminates trunk space issues and means everything is set up in one booking. Recommended operators: idrive4x4.com, nomadtours.com and Al Maha Rental (almaharental.com). Cars like the Nissan X-Terra aregood and you can get camping gear separately through Nomad Tours; the separate gear setup ate trunk space so a combined booking is preferable. Collect the car first thing on Day 1 rather than waiting until Day 2; you need it to visit the mosque and the Mutrah area efficiently.
Sultan Qaboos Grand Mosque: the largest mosque in Oman, completed in 2001 to mark 30 years of Sultan Qaboos's reign, capacity 20,000. Inside: a single hand-woven Persian carpet covering 4,343 square metres and one of the largest chandeliers in the world. Non-Muslim visitors can enter between 8 am and 11 am, Saturday to Thursday only; closed on Fridays. Dress code is strict: shoulders and knees covered for both genders, women require a headscarf. The building is worth 90 minutes. Go in the morning before the heat builds.
Mutrah: the old port district, 15 minutes from the mosque by car. Mutrah Souq is Muscat's most characterful market: a covered labyrinth of alleys selling frankincense, khanjar daggers, silver jewellery, spices, abayas, and tourist goods ranging from excellent to terrible. It is more tourist-facing than the interior souqs you will see in Nizwa, but big and genuinely easy to get lost in for an hour. Buy frankincense here if you want to take some home; the quality is good and the prices honest.
From the souq, walk the Mutrah Corniche west toward Old Muscat. The walk to Al Alam Palace takes about an hour at a relaxed pace (4 km). The palace itself is the Sultan's ceremonial residence, in its current gold-and-blue form since 1972, flanked by the 16th-century Portuguese forts of Al Jalali and Al Mirani on either side. You cannot enter; the exterior and the waterfront approach are the point. The forts are a reminder that Muscat was an important Portuguese outpost from 1507 until the Omani reconquest in 1650, and the architecture of the old fortifications reflects that particular chapter clearly.
Muscat is the only place in Oman where free camping is not practical. Stay in a hotel for the first and last nights.