Irkutsk is one of the largest cities in Siberia and the administrative centre of Irkutsk Oblast. Irkutsk Region is located in the southern part of Eastern Siberia in the upper basins of the Lower (Nizhnyaya) Tunguska, Angara, and Lena rivers. Lake Baikal is located in the southeastern part of the region.

Irkutsk is in many ways the heart of Siberia, with its proximity to Lake Baikal, status as a major transportation hub on the trans-Siberian railway, and a plethora of scientific and research institutes, including a branch of the Siberian Academy of Sciences.

In the late 19th century, gold was discovered in the nearby Lena Basin, and the Siberian Gold Rush began. People came to the region hoping to strike it rich, and those who were successful built sprawling classical mansions and financed public buildings, some of which still stand today.

Lake Baikal is unique. It has a volume of 23 000 km3 or 20% of the world's freshwater reserves, a surface area of 31 500 km2, and a maximum depth of 1637 m. The region's river network belongs to the basins of two of Siberia's largest rivers, the Lena and the Yenisei.

The region's great extent and rugged relief are the reasons for the varied climatic conditions. Temperatures consistently remain below 0 °C for 160 to 180 days of the year. Winters are cold (January temperatures range from -17 °C to -33 °C); summers are hot and dry in the first half (July temperatures range from +17 °C to +33 °C) and rainy in the second half