Noi Bai International Airport in Hanoi
Noi Bai airport is 35 km north of Hanoi, and it takes 45 minutes to one hour by car or bus to get into the city.
There are plenty of taxis, operating out of two stands just outside.
The drivers on the right wearing blue shirts charge $10 USD, the drivers on the left wearing white shirts charge $12.
Another option is taking the Vietnam Airlines minibus just outside the terminal.
It leaves every half hour, costs $2 USD, and makes several hotel stops prior to its final stop at the Vietnam Airlines office just southwest of the Old Quarter.
When you leave Vietnam from Hanoi, you will be charged an exit fee of $12 USD.