All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.
The scholars of the Permanent Committee for Fataawa in Saudi Arabia advised that it is impermissible to build the 'Unknown Soldier Monument', which is similar to the memorial about which you are asking.
The question addressed to the Permanent Committee was as follows: “What is the ruling on erecting monuments and what is known as the 'Unknown Soldier Monument'?”
The answer reads:
“Erecting monuments for prominent figures who played a role in developing the country in the scientific, economic, or political fields and erecting what is called the 'Unknown Soldier Monument' is an act of Jaahiliyyah (pre-Islamic time of ignorance). It is a form of undue exaggeration, as we find them holding commemoration parties around these monuments and putting flowers on them to honor them. This is similar to the times of idolatry and is a means that leads to major shirk (associating others with Allaah in worship), we seek refuge with Allaah from that. Such traditions should be put to an end to preserve the belief of tawheed (i.e. oneness of Allaah), to prevent extravagance without benefit, and to avoid imitating the disbelievers in their customs and traditions, which only lead to serious evils.”
Allaah knows best.