The Assumption Cathedral is the main and largest church of the Achair Women's Monastery, serving as the center of its liturgical and spiritual life and stands out among the entire monastery complex with its architecture. Construction of the cathedral began in the spring of 1998, and by the beginning of 2000, the last, ninth dome was installed, giving the church a completed appearance. The first Divine Liturgy in the fully constructed Assumption Cathedral took place on August 28, 2000. The project of this unique temple was developed by Gennady Adaev and Tatiana Stolbova.

Worship services in the cathedral began as soon as there was a place for the clergy: molebens and akathists, and later liturgies were conducted right on the construction site. The uniqueness of the Assumption Cathedral is felt from the first steps inside, where a spacious area filled with light and directed upwards opens up. In this space, like a precious gem in a magnificent setting, is the white iconostasis with blue and gold elements, created by the diocesan icon painter and architect Gennady Adaev and carver Vladimir Malykh. Even a person unfamiliar with the canons of church architecture immediately notices the unusual golden carved dome that rises above part of the altar with the throne and harmoniously blends with the iconostasis. The intricate filigree of the Royal Gates reminds one of the highest Heavenly dignity of the One who walks through them. On the massive columns in the floor kiots are placed icons of the Mother of God: "Achairskaya", "Assumption", "All-Merciful", "Seeking the Lost".

The acoustics of the cathedral are excellent: not only do the church choirs sound wonderful, but every word of the service in the altar is clearly heard in the farthest corner of the narthex. Two staircases at the northern and southern walls lead from the upper, light-filled church to the crypt of the cathedral, where the sorrowful heart of the monastery, the Siberian Golgotha, is located. The cave temple, where the Siberian Golgotha is situated, recalls the terrible times of Stalin's repressions and the heavy trials that the Russian Orthodox Church endured with the arrival of the Bolsheviks.

The Siberian Golgotha, a unique temple in the crypt of the Assumption Cathedral, is dedicated to the memory of the Passion of the Lord and the New Martyrs and Confessors of Russia, among whom the New Martyrs of Omsk hold a special place. This three-altar temple embodies the prayerful memory of all our compatriots who passed into eternity during the years of militant atheism. In the center of the crypt, in the floor under the symbolic image of the Bethlehem star, are the remains of people found at the site of nameless graves of the victims of the 8th GULAG colony, washed ashore by the waters of the Irtysh, as well as those discovered during the construction of the monastery.

Today, the Cave Temple houses a relic that attracts numerous pilgrims, the coffin of the holy martyr Silvester, found together with the relics of the Saint on July 21-22, 2005.