Added to Unesco's World Heritage List in 2010, Hanoi's Imperial Citadel was the hub of Vietnamese military power for over 1000 years. Ongoing archaeological digs continue on-site, revealing remains of ancient palaces, grandiose pavilions and imperial gates. The main gate (Doan Mon) is named after one of the gates of the Forbidden City in Beijing. Further back is the imposing and colonnaded French Caserne de la Compagnie d'Ouvriers. At the rear is the Princess Pagoda (Hau Lau), which probably housed imperial concubines.
There are also fascinating military command bunkers from the American War – complete with maps and 1960s communications equipment – used by the legendary Vietnamese general Vo Nguyen Giap. The leafy grounds are also an easy-going and quiet antidote to Hanoi's bustle. Guided tours are 150,000d or you can download the Hoang Thanh Thang Long mobile app.