There is not much information about Magos Architectus Prime Archeomedes other than that he is probably among the best siege and fortifications experts in the Segmentum. He is currently stationed on the Forge World of Nestorium, but he is said to have arrived to Sector Deus from Segmentum Solar originally. Rumours say that his previous contractors - after he fortified their planet - tried to kill him so that he couldn't build another set of fortifications as strong as theirs. Whether it is true or not is unknown but two things are clear - he is very paranoid and he is a great architect. He is also known to be a supporter of Nestorian Learners.
In 310.M41 Magos Prime Archeomedes was contracted by Ghosts of Retribution to build them a Fortress Monastery on Mormark. It took seven years to complete, but by 317.M41 Archeomedes unveiled a real masterpiece - the Tombstone. Archeomedes designed all of it himself, tower by tower, trap by trap. Because of this he probably knows it better than anyone else alive.