Historically, the palace was very important. This is where the tanks crashed through the gates and signalled the end of the Vietnam War. The surrender papers were signed here and North Vietnam was officially reunified with South Vietnam, thereby giving the palace, formerly known as Independence Palace, a new name.
There were many interesting photos. The one below shows the tanks breaking through the gates and making a mess of the front lawn.
For a better explanation, you can check out this web page.