This is a 1909 picture of the fortress. According to Wikipedia:

At the northeast corner of the town is a huge fortress known as the Princess Castle dating from the Yuan Dynasty (1277-1367 CE), and the subject of many colourful local legends. A ruined Zoroastrian temple is located near the fortress.

Sadly, the fortress has been systematically plundered for stone, and now very little of it remains. A lot of the destruction happened in the last years.