hà = river, nội = within → hà nội = within rivers, surrounded by rivers

sources

google travel

unesco world heritage sites

unesco intangible world heritage

natgeo hanoi guide

lonely planet hanoi guide

traditional villages 1

traditional villages 2

top 4 mountain passes of vietnam

paperworks

budget

other things to consider: plane tickets to SFO, visas ($25 for you), souvenirs, gifts, accidents etc.