The tickets will be valid until late this month.
The bus tours which run from 9 a.m. to 5 p.m. daily take visitors through tourist attractions including St. Joseph's Cathedral, Thang Long Imperial Citadel, Ho Chi Minh Mausoleum, Tran Quoc Pagoda, Hoa Lo Prison, the Temple of Literature and the Opera House.
The buses will depart every hour from Dong Kinh Nghia Thuc Square near the Hoan Kiem pedestrian zone.
Hanoi opened double-decker bus tour in May 2018 with ticket prices ranging from VND196,000 ($8.48) to VND650,000 ($28).
The free tours are being offered as Vietnamese authorities try to take advantage of the country hosting Southeast Asia’s largest sports event to boost its tourism image and attract more foreign tourists in the post pandemic new normal scenario.
The central province of Quang Binh is offereing free tours to Son Doong, the world's largest cave, to two most outstanding athletes at this year’s SEA Games.
The 31st SEA Games, a biennial regional multi-sports event, is being held in Hanoi and 11 northern provinces. More than 5,000 athletes are competing in 40 sports.