1.  The best activity for tourists is to visit the old quarter, which is an area in the city center with narrow streets, small shops, and old buildings. You will find a lot of people there and some small restaurants. I suggest that you should go to the Hanoi Opera House, which is famous for its unique architecture. It was built in 1907 and has been used as a theater since then. This place is a great place to see traditional Vietnamese performances. There are many museums in Hanoi that can be visited by tourists such as Hoa Lo Prison or Ho Chi Minh Mausoleum Museum and others.

2.  There are many customs in Vietnamese culture that are important to know about. Here are two of them:
1. The Tet holiday is a time when people gather together with family and friends to celebrate the new year. It is a time for family reunion, homecoming, reunion with friends and relatives, as well as sharing joy with others.
2. Greeting people with "Chuc Mung Nam Moi" means Happy New Year in Vietnamese language.