Tang-i Ab Valley with its namesake river situated in the north of Firuzabad Plain, is the only way connecting the plain to the northern districts of Fars Province mainly Shiraz. Some of the most important monuments of the early Sassanian dynasty (mainly belonging to the time of Ardashir I Papakan) are located within this strategic valley. In a north to south direction, the Sassanian monuments of Tang-i Ab valley are as follows: 1- remains of a tower called locally Naqqareh Khaneh on the ridge of a high mountain looking over the deep shallow gorge and the distant surrounding area, 2- Qaleh Dokhtar which is surrounded by precipitous mountains with a few easily defendable access roads, 3- “Ardashir’s investiture relief” on the right bank of Tangab River, at a height of 4 m above the river bed, 4- scattered remnants of a ruined stone bridge which according to a foundation inscription has been built on the order of the early Sassanian vizier Mehr-Narseh and is located about 100 m to the south of the bridge,  5- the largest and the most dynamic stone relief of the whole era representing in an 18 m long surface the final and conclusive triumph of Ardashir I over Artabanus V.