This image from the Kelmscott Chaucer has proven to be the most valuable piece in finding a proper visual depiction of the Temple of Mars. True to its reputation as one of the most beautiful books ever made, so to is the picture. It carries a lot of what gave me the initial reference in creating my end product. The use of bricks in the walls. The statue of Mars holding his sword above his head and the wolf sitting at his feet eating the dead man. The flames in brazier taking on an almost wood-like quality, simultaneously lighting the room, but also speaking to the outside setting. It's quite a complete image that I think accomplishes its job very well.
The Knight's Tale is based off of a story by Boccaccio's Teseida, one that Chaucer adapted to fit within The Canterbury Tales. From that story we have an image that fits the plot. We can see each of the main characters praying to their respective god. A big difference in this image compared to the previous one is that they are all out in the open rather than within their own individual temples. The praying is also occuring during what appears to be the daytime while The Knight's Tale mentions the praying occurring the knight before.
Rodin's Gates of Hell is quite possibly one of, if not the most famous piece from the artist Auguste Rodin. The piece was initially commissioned to be a part of a new museum in Paris, but was unfortunately shut down before the door could ever be displayed. While the initial inspiration for the piece was Dante's inferno, it has grown beyond it and has become a work for which Rodin has drawn from since its creation. One of the more famous pieces he directly took from this door was the thinker, sitting dead center above where the two doors would part. While this isn't a direct depiction of the Temple of Mars, I still feel that it holds some relevance to the feelings that are felt in the description of the building.
Being a depiction of the Gates of Hell, the door is covered with figures caught in the throes of human emotion. It's a mixture of suffering and excess that go a long way in representing the ideas it's based off of. Similarly, at various points within the recounting of the Temple of Mars, there are descriptions of human suffering and death. Most notably, the deaths of Julius, Nero, and Antonious are mentioned at lines 2031 and 2032. In a way, I feel that it's inclusion here is fitting as a way to draw out the vibe that Chaucer was going for in his descriptions of the Temple of Mars.