The name Truc Bach derives from an eighteenth-century summer palace built by the ruling Trinh lords which later became a place of detention for disagreeable concubines and other "errant women", who were put to work weaving fine white silk, truc bach. The palace no longer exists but eleventh-century Quan Thanh Temple (daily 8am–4.30pm; 2000VND) still stands on the lake's southeast bank, erected by King Ly Thai To and dedicated to the Guardian of the North, Tran Vo, who protects the city from malevolent spirits. Quan Thanh has been rebuilt several times, most recently in 1893, along the way losing nearly all its original features, but it's well worth wandering into the shady courtyard to see the statue of Tran Vo, cast in black bronze in 1677 and seated on the main altar. The statue, nearly 4m high and weighing 4 tonnes, portrays the Taoist god accompanied by his two animal emblems, a serpent and turtle; it was the creation of a craftsman called Trum Trong whose own statue, fashioned in stone and sporting a grey headscarf, sits off to one side. The shrine room also boasts a valuable collection of seventeenth- and eighteenth-century poems and parallel sentences (boards inscribed with wise maxims and hung in pairs on adjacent columns), most with intricate, mother-of-pearl inlay work.

The gate of Quan Thanh is just a few paces south of the causeway, Thanh Nien, an avenue of flame trees that is a popular picnic spot in summer when a cooling breeze comes off the water and hawkers set up shop along the grass verges. Where the road bears gently right, keep your eyes peeled for a small memorial in the pavement on the Truc Bach side, which is dedicated to teams of anti-aircraft gunners stationed here during the American War. In particular the memorial commemorates the downing of Navy Lieutenant Commander John McCain, who parachuted into Truc Bach Lake in October 1967 and survived more than five years in the "Hanoi Hilton" to become a US senator and a strong supporter of normalization between America and Vietnam.

Continuing along the causeway you come to Hanoi's oldest religious foundation, Tran Quoc Pagoda, occupying a tiny island off Thanh Nien in West Lake (daily 7–11.30am & 1.30–6pm; free). The pagoda's exact origins are uncertain but it's usually attributed to the sixth-century early Ly Dynasty during a brief interlude in ten centuries of Chinese domination. In the early seventeenth century, when Buddhism was enjoying a revival, the pagoda was moved from beside the Red River to its present, less vulnerable location. Entry is along a narrow, brick causeway lying just above the water, past a collection of imposing brick stupas, the latest of which – towering over its more modest neighbours – was erected in 2003 on the death of the then master of the pagoda. The sanctuary's restrained interior and general configuration are typical of northern Vietnamese pagodas though there's nothing inside of particular importance. Note that visitors are requested not to wear shorts.