A traditional house in Irkutsk

Irkutsk (Ирку́тск), the chief town of the Irkutsk Oblast, is one of the most important places in Siberia, being not only the principal commercial depot north of Tashkent, but also a fortified military post, an archbishopric of the Russian Orthodox Church and the seat of several learned societies. It is situated in , 5185 km by rail from Moscow. Pop. (1875) 32,512, (1900) 49,106, (1975) 500,000, (2002) 593,400. The town proper lies on the right bank of the Angara, a tributary of the Yenisei, 45 m below its outflow from Lake Baikal, and on the opposite bank is the Glaskovsk suburb. The river, which has a breadth of 1900 ft. (579 m), is crossed by a flying bridge. The Irkut, from which the town takes its name, is a small river which joins the Angara directly opposite the town, the main portion of which is separated from the monastery, the castle, the port and the suburbs by another confluent, the Ida or Ushakovka. Irkutsk has long been reputed a remarkably fine city — its streets being straight, broad, well paved and well lighted; but in 1879, on the 4th and 6th of July, the palace of the (then) Governor General, the principal administrative and municipal offices and many of the other public buildings were destroyed by fire; and the government archives, the library and museum of the Siberian section of the Russian Geographical Society were utterly ruined. On July 27, 2004, Irkutsk's synagogue built in 1881 suffered from an electrical fire. A cathedral (built of wood in 1693 and rebuilt of stone in 1718), the governor's palace, a school of medicine, a museum, a military hospital, and the crown factories are among the public institutions and buildings. Irkutsk grew out of the winter-quarters established (1652) by Ivan Pokhabov for the collection of the fur tax from the Buryats. Its existence as a town dates from 1686.

The most significant person in the religious life of Irkutsk is Saint Innocent of Irkutsk (1797–1879, born Ivan Veniaminov) who was born near to Irkutsk, later in Orthodox priesthood. He did missionary travels with his family to the Aleutians. He learned local languages and translated the gospels and the hymns. Later, after his wife died, Veniaminov became a monk, Innocent. He was raised as a bishop, and then the archbishop of Irkutsk (till 1867 when he was appointed to the metropolitan Moscow). His title as a saint is "Miracleworker Innocent of Irkutsk".