Reszer not only created "The Iron Star" he also created "The Compound" which was a scientific facility in the outskirts of the capital city "Tentra". He created the facility with almost all Iron, and some stone.
"The Compound" was one of Reszer's main lab facilitys, he lived most of his time there, he was the only one with a grand bedroom. Reszer wasn't just a genius in the eyes of most regular Humans' he was more or less a god.
Rezser went on to create weapons that were technologically advanced for "The Great War", a water system, sewer systems, vaporizers, farm harvesters, SpaceCraft, Glowstone, Lava/Water towers, and most importantly the Tentra Castle/Isle.
The last recorded history date with Rezser in the text was 987YU, he was explained as being very old, over 100, but looks like he is in his 60's. Apparently after "Invasion Of Moristen" in 985YU he disapeered from Tenta, Rinca, Ritv, and Coris.