hanoi = perpetual building site.
every single building and every piece of infrastructure has been or is being replaced since the introduction of market economy.
maybe you are less sentimental about old houses when you have seen your city destroyed to the degree people have here. let us recount: when the french were thrown out, they burnt down the temples as they left town; and when loosing their war, the americans in a week dropped bombs on hanoi with more explosive power than the two nukes detonated in hiroshima and nagasaki. together.
somehow the vietnamese still manage to be polite, if somewhat formal, towards foreigners.