Thái Nguyên is a city in Vietnam. It is the capital and largest city of Thái Nguyên Province. The city is listed as a first class city and is the ninth largest city in Vietnam. It has long been famous throughout Vietnam for its Tân Cương tea, among the most recognized Vietnamese tea regions. In 1959, it become the site of Vietnam's first steel mill, and is now home to a large and growing major regional university complex.

Núi Cốc Reservoir is a man-made lake, approximately 25 kilometres (16 mi) west of the city of Thái Nguyên in Thái Nguyên Province, Vietnam, in Tam Đảo National Park. It is a popular visitor attraction on account of the legend associated with the 89 islands within the lake.