Iran is the cradle of some of the oldest religions in the world. Mazdakian , Bahai Zoroastrian and Manavian are main religions that started in Iran. Although the Mazdakians are very rare nowaday, however there are quiet a few group of Zoroastrian and Manavians minorities still living in Iran. the Baha'i is not a recognized sect by the government , but its followers chose to continue living in Iran. nowadays Islam is the main religion in iran.
The most important religious site in Iran:
Imam Reza shrine in Mashhad is a complex which contains the mausoleum of Imam Reza , the eighth Imam of Twelver Shi'ites. It is largest masque in the world by dimension and the second largest in capacity. Also contained within the complex include: the Goharshad Mosque, a museum, a library, four seminaries, a cemetery, the Razavi University of Islamic Sciences, a dining hall for pilgrims, vast prayer halls, and other buildings.
This complex is the center of tourism in Iran.The shrine itself covers an area of 267,079m2 while the seven courtyards which surround it cover an area of 331,578m2 - totaling 598,657 m2 (6,443,890 sq ft).
Every year the ceremony of Dust Clearing is celebrated in the Imam Reza shrine.
The shrine of Fatema Mæ’sume (sister of Imām Reza) is located in Qom which is considered by Shia Muslims to be the second most sacred city in Iran after Mashhad. Much of the shrine complex was first built by Shah Abbas I in the early 17th century. The shrine has attracted to itself dozens of seminaries and religious schools. The shrine is also depicted on the reverse of the Iranian 50 rials coin, issued since 2004.
The mosque consists of a burial chamber, three courtyards and three large prayer halls, totalling an area of 38,000 m2(410,000 sq ft). The three prayer halls are named: Tabātabā’ī, Bālā Sar, and A‘dham.
Shāh Chérāgh (brother of Imam Reza) is a funerary monument and mosque in Shiraz, housing the tomb of the brothers Ahmad and Muhammad, sons of Mūsā al-Kādhim and brothers of ‘Alī ar-Ridhā. The two took refuge in the city during the Abbasid persecution ofShia Muslims.
The tombs became celebrated pilgrimage centres in the 14th century when Queen Tashi Khatun erected a mosque and theological school in the vicinity.
Shāh-é-Chérāgh is Persian for "King of the Light”. The site was given this name due to the nature of the discovery of the site by Ayatullah Dastghā’ib (the great grandfather of the contemporary Ayatullah Dastghā’ib). He used to see light from a distance and decided to investigate the source. He found that the light was being emitted by a grave within a graveyard. The grave that emitted the light was excavated, and a body wearing an armor was discovered. The body was wearing a ring saying al-‘Izzatu Lillāh, Ahmad bin Mūsā, meaning "The Pride belongs to God, Ahmad son of Musa”. Thus it became known that this was the burial site of the sons of Mūsā al-Kādhim.