Nizwa Fort is one of the oldest forts in Oman and lies in A'Dakhiliyah Governorate. It has a unique large round shape. Its height reaches 24 metres, with an outer diameter of 43 metres and an inner diameter of 36 metres. This fort has seven wells and multiple openings for stationing the fighters defending the fort. Nizwa Fort was built by Imam Sultan Bin Saif Al Y`aribi in the middle of the seventeenth century. It was this imam who expelled the Portuguese from Oman. The fort, which took 12 years to build, is linked with a castle by means of intricate corridors. Near the fort and castle is the traditional Nizwa market famous for its artefacts.