Shushtar was of utmost importance as the capital of Khuzestan Povince due to its historical values. Shushtar Castle had a role in monitoring the efficiency of Shushtar Hydraulic Systems. Shushtar Salasel Castle is a huge fortress containing several yards, barracks, stables, bathrooms, shabestans, towers, gardens and etc. This castle as well as other 15 monuments of Shushtar was registered in UNESCO World Heritage as the tenth Iranian monument.