The old part of Hanoi is the hart of the city. I personally would advise to stay in a hotel just outside of the old quarter because it is very busy and load. The streets and old architecture are wonderful to look at. We stayed for 7 days and could explore most of the the places to go. If you enjoy the exciting pace, are used to busy city’s and want the next level, then Hanoi is for you. Trying to cross a road is an experience you need to do , but be careful!! If your an experienced traveler in Asia you will be fine alone , if not use a guide!!!! Train Street will definitely blow your mind !!! Fantastic city to visit for at least 3 days.