In the 14th century, Metropolitan Peter of Moscow and All Russia persuaded Grand Duke of Moscow Ivan I (Ivan Kalita) that he should build a cathedral to the Theotokos in Moscow like the Cathedral of the Dormition in the capital city Vladimir. Construction of the cathedral began on August 4, 1326, and the cathedral was finished and consecrated on August 4, 1327. At that time Moscow became the capital of the Vladimir-Suzdal principality.
Saint Peter, Metropolitan of Moscow, died on December 21, 1326 and was buried in the Dormition Cathedral. By the end of the 15th century the old cathedral had become dilapidated, and in 1472 the Moscow architects Kryvtsov and Myshkin began construction of a new cathedral. The first transfer of Saint Peter's relics back to the cathedral was on July 1, 1472 and a feast day was established. Two years later, in May 1474, the building was nearing completion when it collapsed due to earthquake. The foundation for the new cathedral was laid in 1475, and in 1479 the new cathedral was consecrated by Metropolitan Gerontius. The second transfer of the relics of Saint Peter was after the consecration of the Dormition Cathedral, on August 24, 1479, and the July 1 feast day was replaced.
There was also a feast day of the appearance of the relics of Saint Peter (August 4) upon the occasion of an appearance to the wife of Ivan the Terrible (1533-1584), the Tsaritsa Anastasia (1547-1560). Saint Peter appeared to Tsaritsa Anastasia and would permit no one to open his grave. He commanded the grave to be sealed and a feast day established.
The relics of the Saint Peter of Moscow thus rested in the cathedral, but after the invasion of the Poles, who had stolen the precious silver coffin, they were put under cover and remained in this position until 1812. This year Napoleon opened the tomb of the Saint, probably with the same intent as the Poles. Upon the removal of the French from Moscow, Archbishop Augustine of Moscow solemnly discovered the imperishable relics of Metropolitan Peter, and they were carried around the Dormition Cathedral when it was consecrated on August 30, 1813.
Three epistles of Saint Peter are preserved. The first was to priests with an exhortation to pursue their pastoral service worthily, and to tend their spiritual children with zeal. It concluded with an account of Church law concerning widowed priests, and intended to protect them from reproach and temptation. He advised them to settle in a monastery, and for their children to be enrolled in a monastery school for upbringing and instruction. In the second missive, the Saint urged priests to be true pastors and not hirelings, and to be concerned about the strengthening of themselves with Christian and pastoral virtues. In the third letter, Saint Peter again exhorts priests concerning their pastoral obligations, and he urges laypeople to fulfill the commandments of Christ.
Prominent in church-state affairs, there was good reason even for his contemporaries to compare Saint Peter with Saints Basil the Great, Gregory the Theologian and John Chrysostom. The principal effort of Saint Peter was in the struggle for an unified Russian state and the blessing of Moscow as the unifier of the Russian land.