Line 2A, Hanoi Metro (Cát Linh–Hà Đông), also known as Cát Linh line, is an elevated mass transit railway line, and part of the Hanoi Metro network. It is the first rapid transit line to operate in Vietnam, and was opened for service on 6 November 2021. The 12 station line starts at Cat Linh in Dong Da District, passes through Thuong Dinh in Thanh Xuân District and ends at Yen Nghia in Ha Dong District.