At around 5 am, thousands of people gathered at Ba Dinh Square to attend the flag-raising ceremony.
Lots of people wore T-shirts featuring the national flag image.
On Hoan Kiem Pedestrian Street, many people donned Ao Dai (Vietnamese traditional long dress) in the streets, singing and expressing their pride and joy on Capital Liberation Day.
Nguyen Thi Minh Thoan from Hoan Kiem District said that she and her friends got up at 4 am to prepare for the celebration.
Many people travelled hundreds of kilometres overnight to Hanoi to experience the anniversary.
Vu Van Dinh, 76, from the northern province of Hai Duong, said that he travelled with his family and comrades to Hanoi early in the morning. He was an air defence soldier stationed in Hanoi in 1972. This was an occasion for him and his comrades to recall war memories.
Phung Hung Street attracted many visitors.
