The John-117 Monument was a comprehensive diorama of the Second Battle of Mombasa, created in honor of MCPO John-117. Though the battle depicted in the diorama never actually occurred, the monument summarizes the final days of the Human-Covenant war and John-117's sacrifice as in one scene rather than accurately replicating the actual events.
Beginning in 2607, the UNSC began commissioning artists to help with the construction of the monument and the museum enclosing it. All of the character, firearm, vehicle, and landscape models were created by hand, both in real life and canonically, with the likenesses of each human soldier based on "Marine induction scans" and postmortems of dead Covenant troops recovered after the battle.
Only the men and women who participated in the battle knew how it really looked. Based on topographical maps taken before, during, and after the fight, artists were able to precisely pinpoint where everything had to go. Architectural records recovered later provided the basis of what the buildings would look like, but it was the artists' jobs to place each point of damage accordingly. They worked fiercely to recreate the amount of damage the city sustained, from bullet holes and craters, to the chunks of missing walls and the exposed re-bars within. Completed in 2610, a documentary began to be produced, to chronicle the making of the monument, the soldiers' reaction to it, and the museum itself. Some soldiers would visit sites where they fought, often describing their situation at the time.
- The massive diorama of the John-117 Monument is over 1,200 square feet in size and over twelve feet tall. The Human and Covenant figures were all handcrafted, each standing eight to twelve inches in height. No machines were used to construct the molds. The set and vehicles were built by New Deal Studios and the figures were supplied by Stan Winston Studio.
- The Second Battle of New Mombasa is considered to be non-canon; it was part of Microsoft's Halo 3 Ad Campaign and not Bungie's work. Microsoft at that time had no control or idea of Halo 3's story, and therefore it is not present in said canon. Also, it does not appear in Halo 3 or Halo: Uprising.
- A Spartan Laser can be found on the Covenant side of the destroyed bridge, near where Jackson Law is in a Warthog.
- Parts of the destroyed New Mombasa Orbital Elevator are found near where Thomas P. Porter's Scorpion is located.