Coordinates: 51°06′11″N 106°41′12″E / 51.10306°N 106.68667°E
Novoselenginsk (Russian: Новоселенги́нск) is a rural locality (a settlement) in Selenginsky District of the Republic of Buryatia, Russia, located on the Selenge River south of Lake Baikal. Formerly called simply Selenginsk, it was one of the most important towns in Siberia before 1800.
The modern urban-type settlement of Selenginsk, located 115 kilometers (71 mi) to the north, is unrelated to this settlement.
The first fortified settlement of the Russians on the Selenge River, Selenginsky ostrog was located north of the confluence of the Chikoy and Selenge Rivers on the Selenge's right bank. The ostrog was founded by Gavril Lovtsov in 1655, and was located about 20 kilometers (12 mi) southeast of Lake Gusinoye and 85 kilometers (53 mi) southeast of Lake Baikal. The Selenge River soon became part of the main Russo-Chinese trade route, which, by boat, led through Siberia to Lake Baikal, up the Selenge, and then by caravan southeast to Peking. Consequently, the ostrog soon grew and became a major administrative center of the Transbaikal region.