A really great place and extremely popular. It's very large though so it's still very pleasant. Lots of history both thousands of year old and 10s of years old. Lots of information both in Vietnamese and English. Lots of toilet stops are dotted around too. There are also many small exhibition sites all over the place with artefacts.
A UNESCO World Heritage Site that is easily accessed, this makes it worthy of a visit as it is. Its importance to Vietnamese history as well as the pretty impressive architecture remaining makes it a must-see for a visit in Hanoi.
Old citadel with parts built by the french, undergoing some renovation but you can still go in and see operations room used during Vietnam war.
Mon-Su: 09:00-17:00