Taq-e Bostan is a series of large rock relief which dates back to the era of the Sassanid Empire of Persia, during the Iranian dynasty. The Sassanid Empire ruler over western Asia from 226-650 AD. This Sassanid art is located 5 km from the city of Kermanshah in western Iran. The rock relief holds 30 surviving Sassanid relics of the Zagros mountains. The rock reliefs have two big and small arches.
The site features a 1,700 year old base relief dedicated to Mithras. Taq-e Bostan also features reliefs illustrating the crowning ceremonies of Ardashir I and his son, Shapur I, Shapur II and Khosrau II. The hunting scenes of Khosrau II are also depicted on the rocks.
The British Museum had agreed to lend the artefact – a 6th century Babylonian treasure, regarded as the world’s first declaration of human rights – to the National Museum of Tehran back in September, but then delayed the cylinder’s transfer citing the “political situation” in post-election Iran. Last week, the British Museum declared its intention to delay the loan of the Cyrus Cylinder once again, until the summer in order to complete research, sparking an outraged reaction from Iran’s state cultural organisation.
Mithras, also sometimes called Mithra, is a mysterious ancient Persian god, whose popularity resurged amongst Roman soldiers between the 1st and 4th centuries AD. 'Mithraism' is known by historians as a 'mystery cult', because of a lack of clear evidence as to its belief system, traditions and practices. What is known, from surviving records and excavated 'Mithraea' (ie Mithraism places of worship), is that it was a 'closed' religion, available only to male participants who had completed a set of seven initiation ceremonies; that worship involved ritual feasting; and that the most important depiction of Mithras was in the 'Tauroctony' - the killing of a bull. Many other arguments and theories surrounding the religion are largely subject to speculation.
Iran has followed through on its threat, lodged in October 2009, to 
