Nizwa Fort is the most imposing castle in Oman. Built between 1649 and 1668 by Imam Sultan bin Saif al-Yarubi, it is dominated by a huge circular drum tower, 40 metres in diameter and 30 metres high, with cannon embrasures pointing in every direction. It was designed in the gunpowder age to absorb cannon fire — the solid earth filling under the tower platform soaked up impact.
Climb the tower for the best view in town: the date palm oasis stretching out along the wadi, the dome of the new Sultan Qaboos Mosque, and the ridges of the Hajar Mountains behind. The lower levels are now a well-curated museum on Omani daily life — falaj irrigation, frankincense, halwa-making, traditional weaponry. Open daily; entry around 5 OMR. Allow at least two hours.