Taq-e Gara - Credit: Wikimedia Commons
Taq-e Gara or some times Taq-e Shirin is a stone structure in Iran which belongs to the Sasanian Empire. It is built in the Patagh Pass in the heights known as the Gate of Zagros in Kermanshah Province of Iran. This structure is located on the way from Kermanshah to Sarpol-e Zahab, on the 15th kilometer from Sarpol-e Zahab; beside an ancient paving which connects the Iranian Plateau to Mesopotamia. Due to changes of the path, now it is located below the road slope. Read more on Wikipedia
Source: en.wikipedia.org